Part of it looks like someone making a lot of smallish payments in an inefficient way.

Consider this analogy;

Early one morning a stranger arrives in a small town.
He walkes into a cafe, takes a $10,000 wad of bills out of his right pocket, buys breakfast and puts the wad in his left pocket.

After breakfast he takes a cab to the main street, again taking out and putting
away his wad to pay the driver.

Around town he buys a pack of gum, some new boots, 37 gallons of treacle, twelve feet or rubber hose and a stuffed badger.

At lunchtime the stranger has spent $400 and has $9600 left.

The town statistician watches the stranger move money between his left and right pockets and counts the strangers activites as $70,000 moving that morning and a few people get excited.

If the stranger was using bitcoin we would see a transaction splitting 1000 BTC into 1BTC (for breakfast) and 999BTC (the strangers change).

We can't tell what the stranger was doing so we can't be certain if the 999 BTC was a payment or change.

Clicking around in blockexplorer, back in block 196248 there is a balance of 25000 BTC which then moves many times with smaller amounts of BTC splitting off, currently unspent.

It goes back further than that but that's as far back as I can be bothered to click.

Seventy blocks later the big balance is down to about 16000 BTC.

It looks like someone making a lot of smallish payments from a big balance.

If they did it all at once the money would still be distributed the same way but it would take less space in the blockchain and the BTC moved statistic would be smaller.

(or I could be talking nonsense again)

The OP already said he is running 0.6.2

0.6.2 supposedly fixes a theoretical attack that could cause clients to not keep up with the network but it seems to contain a bug that results in it not keeping up with the network .

I also had the problem that 0.6.2 didn't download any blocks after installation.
I am using the linux version on Centos 6

It had 8 connections to the bitcoin network but no blocks downloading.

It started working when I manually told it to connect to another nodes

./bitcoin-qt -addnode=91.210.181.21

I think there is a bug in there somewhere.

BTC-E reported compromised by Phantomcircuit on bitcoinmedia.

Looks like they do a tiny fraction of BTC exchange volume but run to pull your money out if you are a customer.

I trying out bitcoinica with a bit of money I'm willing to loose for the entertainment value.

The market moved in my favour for five or ten minutes. The spread on bitcoinica widened to $0.4 so the profit available to me was not as much as I expected. I could leave a limit order on bitcoinica and have the mtgox price swing 5% or more past it and not get my order executed.
It's an extra risk I wasn't totally aware of.

Bitcoinica is badly documented. For example I can't find any official explanation of the * that sometimes appears next to buy or sell when the market moves.
Seems to mean no liquidity, you won't get an order executed right this moment?

Bitcoinica does not full details of company registration or office address. The domain uses a whois privacy service. It is possible they could just dissapear.

I think I am playing with fire. It's fun but if I'm drunk, tired or impetuous I'm going to get burned.

Bitcoincharts.com is nicer to use than mtgox charts.
Their charts don't need some terrible javascript to bog down the browser for five minutes every time.

mtgox charts on bitcoincharts

I'd rather donate direct to the developers. Are they even accepting donations?
I'v looked on bitcoin.org but I can't see an address or any mention of how to donate.

There is also http://www.reddit.com/r/bitcoin

This is not normal. Once a transaction is confirmed it should stay in the list and the balance should not change unless you use some coins.

My first throughts are either the wallet file got lost due to disk corruption or your computer is infected.

Is the computer stable or does it crash ocasionally?
Do you proactise good computer hygiene of not running software from untrustworth sources and have a good up to data antivirus program.

Perhaps people will have more ideas if you say a bit more about your setup start with what operating system?

Paypal's terms and conditions forbid buying and selling virtual currency.
Any use of paypal for bitcoin has a high risk of taking a loss or getting your account closed.

Exchanging your BTC for cash as in actual banknotes means meeting someone in person.

There are a few sites that can help you to find someone in your area.

http://btcnearme.com/
https://bitmarket.eu/faq

There is also the #bitcoin-otc and #bitcoin-otc-eu IRC channels, though these days you have to wait a week after registering and be able to follow the instructions to cryptographically authenticate to get in.

The britcoin price is based on actual reccent trades. I assume bitmarket is the same.