So I started using Instawallet.org and I had a few wallets with 20-30 bitcoins in them each. This morning I went to transfer bitcoins from one of the wallets and it said "Sorry but something went wrong" and the amount I tried to send vanished from my wallet. The same thing just happened when I checked one of the other wallets I was using with them.

Upon investigating with blockchain.info it's showing that an hour after I deposited 32 bitcoins into instawallet.org they were split up and transfered to multiple other addresses. Following the trail the coins were split and forwarded to different addresses about 4 times.

On the second wallet that this happened on it shows I deposited 27.14 bitcoins and an hour later 499.997 bitcoins were transfered from that address to another address. My wallet only had 27.14 bitcoins in it so I'm not sure how 499.997 was sent out of it...

Can anyone explain what's going on? Am I just reading blockchain.info incorrectly? Is the error and vanishing bitcoins just a fluke in the code and doesn't mean the wallets were hacked? Or did my wallets get hacked?