I got past that error by defining -D_WIN32_WINNT=0x0602 -DWINVER=0x0602.  I then ran into undefined WSAPOLLFD and corrected that by adding the definition to winsock2.h. See http://stackoverflow.com/questions/20957727/boostasio-unregisterwaitex-has-not-been-declared for details.

Ron

Has anybody tried building V0.9.0rc1 yet on Windows?  It fails for me on rpcserver.o:

C:/MinGW/msys/1.0/home/rwh/boost_1_55_0/boost/asio/detail/impl/win_object_handle_service.ipp: In sta
tic member function 'static void boost::asio::detail::win_object_handle_service::wait_callback(PVOID
, BOOLEAN)':
C:/MinGW/msys/1.0/home/rwh/boost_1_55_0/boost/asio/detail/impl/win_object_handle_service.ipp:402:5:
error: '::UnregisterWaitEx' has not been declared
     ::UnregisterWaitEx(impl->wait_handle_, NULL);

I'm on Windows 7 and have Boost 1.55 installed.

Ron

The ones that I have seen are caused by modifying the first push-data opcode in the input script, changing it from a 1-byte push-data opcode to a 3-byte push-data opcode.  Since the same amount of data is pushed on to the stack, the script is still valid.  It just changes the transaction hash.

Pieter has listed several things that need to be done.  Canonical push-data scripts are just one of them.  Some of the changes will require changes to all clients in order to implement them (such as fixing malleable signatures).

That said, I did change my node to not relay transactions with non-canonical push-data opcodes.  It seems to be rejecting just the bad transactions, so I'm guessing that existing clients are OK with this change.

I run a full node and I've been seeing a number of double spends in the log.  So it is not just blockchain.info that is detecting the double spends.  For the ones that I checked, they have the same inputs and outputs and were created at almost the same time.  Sometimes they are a double spend, although I found a couple were included in blocks (which could just be the result of a race condition as to which transaction is seen first)

Here are a couple of them:

  6e21cf5c9dc0320d09084a6426ec360f53bfa0fa9f981d4b26e76fd77a19b93c
  20acb23194be4af89538e720af2507c2ad4b0d179fce9c39e3cae0518d6e7593
  15b94449d35dac6c31b181d6384f3120f8caf700e628b6241cce76a0727567ff
  4837a47929d05e723abc8a5b4c50193ed559c4a73537582584db2f8a677554a9
  43ccf90a7b445acc8265d08c9d48ef99ec17337b56effc850977872d567ddada
  66e507b9f079434ff223fdb54f7f1f88695179b38efac5185809387375ad0e6b
  478143a7acd3325ca0218a7d10b43ce16694f5836a7948f13ca90cb024426042

And many more ...

I should add that the node that is reporting the double spends identifies itself as /Satoshi:0.8.99/ and protocol version 70002.  So this might be something in the new client release.  It sends 'reject' messages whenever it is unhappy (which I think is a good thing because it lets you know why a peer is unhappy with you).  It just reported a couple more duplicates and I checked and they are all in the block chain, so I'm not sure what is going on.

Don't delete the blknnnnn.dat files if you want to continue to use Bitcoin-Qt.  Those are the block chain files and will just be downloaded again if you delete them.  They stretch the whole way back to the genesis block when Satoshi created Bitcoin.  If you want to run a lightweight client such as MultiBit, then you can safely delete all of the files after exporting your private keys (you'll need to import them into MultiBit or you could just send the coins from your Bitcoin-Qt wallet to your MultiBit wallet before deleting anything).

The block size is dependent on the number and size of the transactions included in the block.  So it is impossible to guess how big blocks will be in the future and thus how big the block chain will be.  There is currently a 1MB maximum block size, but who knows if that will remain the maximum as the number of transactions increases.  You could just take the current block size (around 250KB) and use that to guesstimate the future block chain size.

You could try starting Bitcoin-Qt with the -rescan option.  This will cause a rescan of the blockchain and should pick up any missed transactions.  This is a lengthy process, so be patient.

Remember to remove the option after it is done so that you don't do the rescan each time you start the client.

Is  bitcoind downloading the block chain?  Have you tried restarting it?

Also, it looks like your P2P port is in use?  Are you running two copies of P2Pool?

You only receive a payment when BTC Guild finds a block.  They had a bad run of luck for 3 hours and didn't find anything, so there were no block rewards during that interval.  There have also been times when they found 4 blocks in an hour, which greatly increases the payments.

The miner prepares work in advance so that it is ready to go when a hash operation is completed for the current work unit.  The message you see occurs when there is not enough work available when it is needed.  There is often a miner configuration parameter to set the size of this queue.  Some miners (such as BFGMiner) will automatically increase the amount of queued work when this happens.

It is a balancing act because the miner doesn't want to request too much work in advance since that can increase the number of stale shares.  But you want to request enough to keep the mining operation going without delays.

Power = (Voltage * Current) for a DC circuit.  This yields the peak power for an AC circuit.  The average power will depend on the power factor (the phase shift between voltage and current) and can be lower for the same voltage and amperage.  So you should not try to draw the maximum rated current for a long period of time.

4000W at 115V is 35A.  Most home circuits are not rated for that kind of current (ranges and dryers are usually 220V to reduce the current required).

Plus, that is 96 KWH per day or 2880 KWH per month.  You should check your electric bill to see what your rate is.  My utility (I'm in NY) charges around $0.08/KWH, so that works out to around $230/month for electricity.

Yes, it is 4 business days.  I've made a number of purchases through Coinbase and never had any problems.  I think some of the delays others have experienced are triggered by the Anti-Money-Laundering rules that banks have to follow.  I tend to make smaller purchases and then wait for each one to be confirmed before initiating a new one.

They will send you an email when your coins are available.

You should always back up your wallet before upgrading any software just in case there is a bug in the new version.  I upgraded Multibit today and had no problems.

The BE Cube doesn't need any special drivers.  It talks to BFGMiner using an HTTP connection, so you need to add "--http-port 8330" to the BFGMiner command line and then point the cube to this port on your local system.

Read all about it here: https://bitcointalk.org/index.php?topic=352658

You want to use MultiBit if you are just interested in having a local wallet.  MultiBit connects to peer nodes running bitcoind or Bitcoin-Qt when it needs block or transaction information, so it doesn't download the entire blockchain to your system.

You don't need a merchant account to  buy and sell bitcoins.  You can send coins from Coinbase to your MultiBit wallet and vice versa.  I think it is a good idea to send the coins you purchase on Coinbase immediately to your wallet (Coinbase pays the miner fee for you).  That way, you have them safe and secure in case anything happens (hackers, bankruptcy, whatever).

No, assuming you are upgrading from 0.8.5, it will use the same wallet and blockchain data.

Yes, it does and is turned on by default in Bitcoin-Qt.  But uPnP has to be enabled by the router.  There is also a problem if more than one computer connected to the router wants to run a full-node, although that could be handled by changing the default port assignment.

Mine varies between 40 and 70.  The number doesn't matter as much as the number of peer nodes downloading the blockchain from me.  My upload bandwidth (5 Mb/s) is maxed out 24/7.  I must just be lucky 

It depends on how the power supply is wired internally as to how much power is available for each output voltage.  The power supply rating is the maximum power you can draw when you add up all of the power being used.  So if you are drawing 100W on the +5V output, then you only have 400W available for the +12V output.

But the specs for the power supply you mentioned explicitly state that the +12V output can draw up to 40A, so there is plenty of power for a single cube (you are not using any of the other output voltages).  When running 24/7, I think you can safely go to 80% of the rated power output without any problems, which would be 384W in your case.