I'm not sure. It isn't the wallet.dat but rather the levelDB databases that Bitcoin Core uses for everything. You should lookup some stuff about levelDB.

Your knowledge is quite wrong. There are most certainly people on the core dev team that have the key. I'm pretty sure that gmaxwell has the alert key because he said this about the recent blockchain fork. He is referring to the alert sent out. Note the "I"

There is in fact an override option that makes an alert cancel proof. Go look in the code. alert.cpp, line 178 https://github.com/bitcoin/bitcoin/blob/master/src/alert.cpp
gmaxwell said it too.

You should include the links to those threads. They aren't linked.

What good would that do? It would cost a lot of processing power and there would be little profit. There would be N times the amount of processing power in order to flood the network with their blocks, but each one different. With that much processing power, it would be more effective and more profitable to mine normally. Instead of finding two blocks simultaneously and getting only a 25 BTC reward, with the same hashrate, they could find two blocks one after each other and get a 50 BTC reward.

The longer a node holds onto a block, the higher the risk of someone else finding that same block and thus orphaning the miner. Unless the miner held a significant portion of the network, he will not be able to mine faster than the rest of the network can and produce a longer chain. Still, the miner that finds a block has a slight advantage over the remaining miners since he has the block before everyone else. Due to network latency and the verification of blocks, the miner who found a block has a slight time advantage over everyone else, but not by much.

If that were to happen, then as gmaxwell said, there would be a new alert that cannot be canceled and cancels all previous alerts that states "Alert Key Compromised" At that point, I would assume that the dev team would change the client to have a new alert key and simply not distribute that key to Gavin, thus solving the problem. However, that is not needed right now and is much more hassle to do because some people would have clients with the old key and some with the new. This means that if an alert was needed such as in the yesterday's problem, the same alert must be sent twice with both key's signatures in order to reach everyone.

What alerts would you not trust? Use your own brain. Obviously an alert such as "URGENT: Upgrade to Bitcoin XT NOW" should probably be ignored. Every legitimate alert sent out links to a page from here: https://bitcoin.org/en/alerts.

The problem is the size. If your <fromaccount> is all of your addresses, then it must search through every single unspent output for every single address in the wallet. Since there are thousands of addresses and thousands of unspent outputs for each address, it can take a long time to search through everything in order to create your transaction.

Unfortunately, I don't know how you can speed this up, and I'm pretty sure that you can't speed it up. I would advise consolidating all of your Bitcoin into one address and create a new account in Bitcoin Core with only that address. It should be faster that way since it will only have to search through I address and a few unspent outputs.

Just run Bitcoin Core and it will do everything it needs. However, if it constantly shuts itself down, that means that it is detecting an error and you should check the debug.log. Also, that points to a larger problem than with Bitcoin Core itself. This usually means that there is something that is messing with the databases. It could be other software or your hardware. Perhaps disable your antivirus and check your hardware. Such issues could be indications of hardware failures.

That is not a full list of everyone who has an alert key. If you actually read the whole thing, you would notice this:
The keyholders are not publicly known for their own safety. If everyone knew who held the alert keys, then people could pressure them and coerce them into sending alerts. However, the alert system is not all-powerful. It is in fact rather weak. It does not force anyone to do anything nor does it force the software to do anything. Anyone with the alert key can only send messages that are up to the people to decide whether to use or not.

There is only one alert key and it is held by multiple people, not just Gavin, and I wouldn't be surprised if more core devs had them. I know that Theymos has a key as well as Gavin. I'm fairly certain that waldimir has one too and probably more if not all of the core devs.

Doesn't necessarily have to cpu mine. The software could also gpu mine and cpu mine, although both are less effective than ASICs. With a large enough botnet, it could be very profitable. Either way, the hacker is still profiting because he has no expenses to pay for using other people's electricity and computing power.

I'm also running out of ideas. Try reinstalling. Besides that, the only thing I can think of is that your hard drive is failing.

This belongs in the lending section. Also, people here won't lens you anything unless you provide a valid collateral. See this topic https://bitcointalk.org/index.php?topic=577765.0 to see what is considered valid collateral.

I would recommend MultiBit or electrum. I have used multibit before and it is pretty good. I haven't used electrum, but from what I have heard, it is a very nice client.

It doesn't matter when you copy the wallet.dat back, as long as it is there and replaces the one that Bitcoin Core generates.

First of all, nothing was ever forced on you. There are several wallets you can choose from, you don't need to use Bitcoin Core.

Now onto fixing your problem. The problem is that you are not allowing Bitcoin Core to shutdown properly. If you simply shutdown your computer, I think it will just terminate the process (doesn't happen on windows 7 but probably does on windows xp). By simply terminating the process for Bitcoin Core, you are corrupting the databases. These need to be shutdown properly. To close Bitcoin Core properly, you must open up the client, go to File > Exit. Then wait for the little window that pops up to go away. This ensures that Bitcoin Core exited properly and that the databases won't be corrupted. Of course, I don't see this problem with Windows 7 because I think it will close each application through the application's shutdown, but windows xp might simply terminate the process.

There are, but they still rely on banks. Right now, the only one I know of is bitwage. They have you add their bank to your employers payroll system and then convert your paycheck to Bitcoin. It obviously still relies on banks for this, so it is difficult to get paid in Bitcoin _without_ relying on banks at all.

Not hard as in the difficulty of getting paid in Bitcoin, but hard as in getting paid in Bitcoin without relying on fiat. Possum577 is saying that it is difficult to get paid in Bitcoin by an employer because they primarily rely on fiat and banks.

Are you sure that the Bitcoin is missing? It seems like the other address it sent to was a change address. Double check your wallet and see if the other address that transaction sent Bitcoin to was a change address.

Yeah. Delete the whole directory and redownload the blockchain. It seems like the files containing the raw blocks was corrupted.

Game on it  You could also try altcoin mining or as TheRealSteve said, use it for other distributed computation projects. You could also sell them for Bitcoin. Go over the the marketplace and put up sell offers for your GPUs. Someone will probably buy them.

Are you sure you sent the Bitcoin to the right address? I have never heard of paymium before, but if they are like every other Bitcoin wallet, they should provide you a transaction id for your transaction. Can you post that here?

Your database is corrupted again, so you need to reindex the whole thing. Anytime Bitcoin Core crashes or you terminate it without letting it shutdown properly, you will need to reindex the database. That should fix your problems.