Wait for a few days. Eventually it will be "forgotten" by the network if it remains unconfirmed. At that point, the transaction should disappear from your wallet and all block explorers. Then you can create a new transaction that has a higher fee so that it will be included in a block by miners.

This is the general principle of CPFP, and it may not be entirely correct.

Step 1: Find the txid of your unconfirmed transaction
Step 2: Calculate the fee for the unconfirmed transaction with a fee of 0.0001 BTC/Kb
Step 3: Create a transaction that spends the unconfirmed transaction to another Bitcoin address. Include in its fee the recommended fee and the fee you calculated in step 2. (e.g. fee of 0.0001 BTC for both transactions means 0.0002 BTC fee in this new one)
Step 4: Sign the new transaction.
Step 5: Push the transaction to the network. It is recommended to use http://eligius.st/~wizkid057/newstats/pushtxn.php because the mining pool Eligius is one of the only pools to implement CPFP. This will push straight to them and the rest of the network.
Step 6: Wait for someone, probably Eligius, to mine a block and include both of your transactions. This could take a couple hours since Eligius has a small percentage of the hashrate of the network.

Congrats! You now have two confirmed transactions

Although your patch was rejected, Bitcoin Core 0.11 includes new code that does blockchain pruning, similar to what your patch does (I think) but in such a way that has been tested and confirmed to work without breaking anything else.

Was that sent before or after the transaction was dropped? It should work if it was sent after it was dropped because then the transaction doesn't really exist. However, before it is dropped, it will be seen as a double spend and the second transaction will not be relayed.

You can't take it back, but after a couple days, if it isn't confirmed, it will be "forgotten" by the network. You won't be able to find it on any block explorer and your client should show that the Bitcoin was never sent. In that case, just resend it but use a higher fee.

You should pay at least 1000 satoshis/kb but I would go with 0.0001 BTC/Kb right now with the current spam situation.

It wouldn't make a difference. As long as the hashrate is the same, blocks will be found with an average of 10 mins between each. Every miner could be solomining and the exact same thing would happen, except one guy would get all 25 BTC instead of having the reward distributed.

Transaction times are instantaneous. Confirmation times are not. I also send my transactions with a 10,000 Satoshi fee, and they confirm anywhere from 5 to 20 minutes. Right now though, there is an ongoing spam attack, so transactions will take longer. It is recommended to use a higher fee right now for anything urgent. Also, your confirmation times vary because of the block time variation. Blocks are actually not found every ten minutes, but on average, are found every ten minutes. Sometimes they come out very quickly, other times it can take up to 2 hours.

Double spending means that the same inputs have been spent 2 or more times. In this case, most of the double spends are from the spam attack which sometimes will send 2 transactions that have the same inputs. A double spend does not duplicate the Bitcoin, but rather screws over one party, the one who the Bitcoin should be sent to. The reason people suggest waiting for a couple of confirmations is because it becomes much much harder to double spend once the transaction is confirmed.

Because there is an ongoing spam attack on the Bitcoin network. Normally this doesn't happen, but with the current spam attack, transactions are becoming delayed because of the massive number of unconfirmed transactions caused by spammers. Just wait and your transaction will eventually become confirmed. Sometimes though, your transaction can be more delayed by what is in it, e.g. dust transactions.

I managed to import it and another address into my wallet and it didn't crash. When I try to send a transaction with all of it though, my wallet says that the minimum fee is 2.24853362 BTC, way more than the amount of BTC in the addresses (0.25...)

What do you mean fake confirmation? As in it is confirmed in a fork and not the real blockchain?

It is not possible. A block is only aware of itself and the block before it. Your node could theoretically record every single fork, but that would take a lot of data since orphan blocks (essentially mini-forks) happen every single day. It would require a connection to every single node in order to catch every single fork.

Someone could mine a fork for a long time, but the only way for it to be accepted is if it is longer and more difficult. The timestamps don't matter. This would only work well if the miner was extremely lucky or had more hash power than the main network (assuming he isn't mining there also).

Actually no. Gavin does not use a private key to lock anything or put anything into a "fixed" state. There is nothing that does this. However, there are several checkpoint blocks hard coded into the code. If your blockchain doesn't match the checkpoint blocks, then all nodes will reject it.

With the current number of users, it is unlikely that they could break Bitcoin besides major cryptography flaws or a 51% attack. If any agency was behind the spam attack, they can't keep it up indefinitely. Even if they could, the community would find new solutions to mitigate and reduce the effects of the spam. Right now one solution is to add a little extra fee, or to configure full nodes to not relay certain transactions. Currently, I think it would be difficult to kill Bitcoin.

It is not possible with Bitcoin Core. You may be able to find some other software which is a gui that uses the RPC Server from the daemon as its backend.

It does that after 48 hours or more, not 24 hours. Eventually, an unconfirmed transaction is dropped after a few days unless someone (e.g. the sender) continues to broadcast it.

Eligius still produces its share of empty blocks. It has a smaller hashrate, so there are less of them.

It saves time because they don't need to go through the mempool and get transactions to add. Also because they always start out with empty blocks. Preventing this would require a code rewrite which takes time and by the time that the code is done and tested, the attack is over and it is pointless.

So you're saying that you are selling visa cards that can be used with paypal for Bitcoin.

Just create a thread and say that you will accept escrow. Let the buyer choose the escrow and then you make sure that the escrow is trusted. The list of trusted escrows is here: https://bitcointalk.org/index.php?topic=108716.0. The deal will typically be carried out through PM unless a dispute is involved.

First of all, this is a BITCOIN site. You aren't going to get any business if you are selling things for PayPal.

As for escrow. How escrow works is that the buyer will send the amount of Bitcoin to be paid to a trusted third party called an escrow. Then the seller (you) will send the item. If the buyer receives the item and it is what he agreed to pay for, he will tell the escrow to release (forward) the Bitcoin to the seller. If the buyer disagrees with something about the item and wishes to dispute what you sent, then the escrow will mediate discussion and decide whether to send the funds to the buyer, seller, or some to both. Sometimes with digital goods, the escrow will receive the digital good and check whether it is what the buyer is paying for. If it is, he will forward the good to the buyer and the bitcoin to the seller, otherwise there will be a dispute.

BTW, this belongs in the marketplace section.

Talk to escrow.ms about having BenAnh removed from DefaultTrust. escrow.ms is the person on default trust who trusts BenAnh, which is why many people will see his ratings. If he is removed, then the rating will stay, but be less noticeable. explain the situation to escrow.ms and explain why you think he might be abusing trust.