Hello everyone I wanted to know how to solve this problem:
C:\Nxt>java -cp Nxt.zip Nxt
[2013-12-01 10:47:15.242] Nxt 0.2.19 started.
[2013-12-01 10:47:15.266] Loading transactions...
[2013-12-01 10:47:15.409] ...Done
[2013-12-01 10:47:15.410] Loading peers...
[2013-12-01 10:47:15.428] ...Done
[2013-12-01 10:47:15.429] Loading blocks...
[2013-12-01 10:47:16.208] ...Done
[2013-12-01 10:47:16.209] Loading accounts...
[2013-12-01 10:47:16.237] ...Done
[2013-12-01 10:47:16.239] Loading assets...
[2013-12-01 10:47:16.241] ...Done
[2013-12-01 10:47:16.241] Loading orders...
[2013-12-01 10:47:16.242] ...Done
Exception in thread "pool-1-thread-2" java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-4" java.lang.NullPointerException
at Nxt$2.completed(Unknown Source)
at Nxt$2.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-3" java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-5" java.lang.NullPointerException
at Nxt$2.completed(Unknown Source)
at Nxt$2.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-1" java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-8" Exception in thread "pool-1-thread-7" java
.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-10" java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-11" java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
C:\Nxt>java -cp Nxt.zip Nxt
[2013-12-01 10:47:15.242] Nxt 0.2.19 started.
[2013-12-01 10:47:15.266] Loading transactions...
[2013-12-01 10:47:15.409] ...Done
[2013-12-01 10:47:15.410] Loading peers...
[2013-12-01 10:47:15.428] ...Done
[2013-12-01 10:47:15.429] Loading blocks...
[2013-12-01 10:47:16.208] ...Done
[2013-12-01 10:47:16.209] Loading accounts...
[2013-12-01 10:47:16.237] ...Done
[2013-12-01 10:47:16.239] Loading assets...
[2013-12-01 10:47:16.241] ...Done
[2013-12-01 10:47:16.241] Loading orders...
[2013-12-01 10:47:16.242] ...Done
Exception in thread "pool-1-thread-2" java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-4" java.lang.NullPointerException
at Nxt$2.completed(Unknown Source)
at Nxt$2.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-3" java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-5" java.lang.NullPointerException
at Nxt$2.completed(Unknown Source)
at Nxt$2.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-1" java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-8" Exception in thread "pool-1-thread-7" java
.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-10" java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception in thread "pool-1-thread-11" java.nio.channels.ReadPendingException
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at sun.nio.ch.AsynchronousSocketChannelImpl.read(Unknown Source)
at java.nio.channels.AsynchronousSocketChannel.read(Unknown Source)
at Nxt$1.completed(Unknown Source)
at Nxt$1.completed(Unknown Source)
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)
at sun.nio.ch.Invoker$2.run(Unknown Source)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Did you delete all your .nxt files before starting up? They may have been corrupted. (Make a backup first)