Since for some reason I'm still in n00b jail, I thought I'd use the time I serve here to be useful
If you follow reddit a bit closely, you'll see there have been several reports of coins stored on BitcoinQT wallet disappearing.
For example:
http://www.reddit.com/r/Bitcoin/comments/1e530j/plz_help_analyzing_stolen_bitcoin_transaction/It turns out there was, and probably still is, a fake bitcoinqt client out there.
This has been discussed on these very forums here:
https://bitcointalk.org/index.php?topic=195666.0So please please please, only download the bitcoin client from the one, and only reliable and trustworthy source:
http://bitcoin.org/en/downloadHave fun!