Since a new address is created for each coin generation during solo mining, you had created many more than 100 new addresses. Two things you could do to see if it was a backup that was compromised instead of your pc.

See if any of the coins that were left behind shared an address with coins that were stolen, if some shared an address then the attacker just went for a round number. If no addresses are shared it might have been a backup that was the problem.

If you sort through all 400+ inputs on the hackers transaction and look for the 101st newest first seen on date, that would give you the approximate time the backup was created.

Is it possible the hacker got a hold of an old backup of your wallet? That would explain the remaining coins if the backup the hacker got was old enough.

The problem sees to come down to Mt.Gox being under staffed.

The owner is then left in the position of either spending his time correcting problems and interviewing potential employees, or spending that time communicating with users.

The current balance of time spent on fixing things vs communication may be less then perfect, but I would rather he spent too much time fixing problems than too much time communicating with users.

The difference between a large pool and a small pool is not how many bitcoins you will get. The difference is how quickly your earnings will approach your theoretical average. Big pools give more consistent earnings. However if one pool gets too large they can pose a risk to the security of bitcoin transactions. The pool's operator would not be able to spend other peoples bitcoins or create additional bitcoins. They could however be able to undo recent transactions and therefore take back bitcoins they had payed to others. That is the reason some people suggest staying away from deepbit.

Difficulty does not increase with time, it increases with the total power of the hardware used for bitcoin mining.

For that reason difficulty will self correct moving towards a point where the most efficient profit enough to continue but not enough to attract more competition.

First thing, what are you paying for power. If you have a competitive rate for your electricity you can stay profitable even in bad conditions.

Second buy hardware that is cheap or popular enough to have resale value avoid the middle ground. Cases are optional especially if you figure on the GPUs being the only thing with resale value. If you have the option of recouping much of the hardware cost your risk is very low.

Lastly consider where you are going to put the mining rigs. If you are going to have a lot of mining rigs you have to figure out how much each circuit breaker can handle and what you are going to do about the heat. Every watt/hour of power used is a watt/hour of heat generated. If you can avoid the need for air conditioning you will save on power.

Mining is the lower risk/lower return way of investing in bitcoin.

Specifically I think it would help to have the ability to reply to a thread without bumping it to the top of the forum. Much like 4chan's sage feature.

This would let people reply with a counter to misinformation without furthering the life of the thread.

Most pools don't offer PPS because if the pool is unlucky the operator loses money on PPS. Also someone who wanted to hurt a pool could use PPS and hold back any shares that were also a valid block. This would cost the attacker very little compared to submitting every share, but would cause the pool operator to lose money.

Have you checked to make sure it was not a change in difficulty that caused your earnings to change?

You should keep several encrypted backups of any wallet that has a balance.

Encryption only helps until you open the encrypted file or container yourself on an infected machine. At that point its just a matter of how smart the malware is.

I am not worried. The 24h trading volume is still very high.

try bitcoin.exe -rescan and see if that helps.

I think it only changes the first time you receive coins at a new address and only if the address that received the coins is still the one displayed. This is to encourage you to use a new address for each transaction. This improves both your ability to track where your bitcoins came from and also your privacy.

Read news articles about anything complicated you have in-depth knowledge of and you will see the same thing. Bitcoin is no different than any other complex subject.

You options are:

Offer products or services for bitcoins, the marketplace forum is a good place to start if you take that approach. To deal with the trust issue consider using a escrow service such as clearcoin. https://clearcoin.appspot.com/

Use one of the exchanges to buy some. Mt.Gox is the largest. You can get funds in through Dwolla or Liberty Reserve.  Dwolla is simpler and cheap but slow. I don't know how fast Liberty Reserve is looked too complicated to bother with when I looked at it.

Use you computer power to help secure the bitcoin network and earn bitcoins in exchange. The mining forum has more information about that. It requires high end GPU(s) preferably AMD ones and some technical knowledge. If you want earnings at a slow and steady rate rather than large amounts rarely you need to join a mining pool.

Slush's pool is still up but not on the pie chart so that is a large chunk of other.

The practical reason is that it helps you know where the bitcoins came from. If you give each person you deal with a different address you know who sent the bitcoins by which address received them. The paranoid reason is that by using a different address each time it makes it harder to tell which transactions came or went from a single person.

You must backup again when the number of times you have sent coins + the number of new addresses you have created is 100 higher than the last time you backed up. For safety you should do so at 50 or earlier. If you want to be paranoid about wallet backups you should back up every time you make a new address or send bitcoins. Receiving bitcoins does not require a new backup.

The wallet stores proof of ownership of an address rather than the bitcoins. The bitcoins are stored on every computer with a copy of the block chain but your wallet is what allows you to spend yours.

The reason you may need a new backup after sending coins is that one or more group of coins you have received is sent with part going to the address you sent them to and the rest going back to you at a new address. If that new address is not in your old backup you will lose those bitcoins.

Bandwidth is not a major issue but high latency puts a bitcoin miner at a disadvantage.

They limit bitcoin withdrawals so that if a hacker gets your password there is a limit to how fast he can steal all your bitcoins. Once they are gone there is no way to get them back.

Dwolla changed their API, MtGox is setting things up to work with the new API until that is finished transfers will be delayed.