I installed Bitcoin-Qt wallet on my Windows 7 PC on 12/1/13 and transferred 0.3 bitcoins from coinbase this wallet. I then transferred 0.2 bitcoins from this wallet to cryptsy. According to blockchain.info
https://blockchain.info/en/address/1BvHrxNdPdzfUAu9YH9QmwRYoJf5YGuWrNnot only did 0.2 bitcoins transfer to cryptsy but my remaining balance 0.1 bitcoins was also transferred to an unknown address. At the time I didn’t realize what had happened because my wallet showed a correct balance of 0.1 bitcoins. Believing that everything was working correctly I then transferred another 7.7 bitcoins from coinbase and transferred 6.8 bitcoins to cryptsy. And again the same thing happened -- my remaining balance of 0.9 bitcoins was sent to another unknown address. My wallet continued to show a correct balance of 1.0 (0.9+0.1) bitcoins so I suspected nothing.
Dude, you didn't lose anything at this stage. Everything is working perfectly.
Check this page to understand the situation.
https://en.bitcoin.it/wiki/ChangeI only discovered the problem when I closed my wallet. When I reopened the wallet it took more than half a day to synchronize and when competed my wallet address changed to a new address with a zero balance. Do I have any recourse in recovering my lost 1.0 bitcoin? My lost bitcoins can be seen at the unknown addresses with blockchain.info and they have not been spent/transferred yet.
Blocks are created around every 10 minutes (less when the network hashrate is increasing). When you reopens the bitcoin-qt after a few days, it will need to download all the blocks for that period, but it usually don't take long unless your network speed is very very slow.
Have you done anything with the bitcoin data directory?
You should have something like 14GB files in the directory.
https://en.bitcoin.it/wiki/Data_directoryIf you accidentally delete the block data, the bitcoin-qt will redownload all the blocks, and will take a long time (just like the initial synchrony).
If you accidentally delete the wallet (wallet.dat), the bitcoin-qt will regenerate a new wallet for you.
It looks to me that you somehow deleted the whole directory, and so it takes a long time to synchronize, and your receiving address changes.
Have you deleted the wallet.dat? If yes, check if it is still in the recycle bin.
Do you have any backup for the wallet.dat? If no, sorry, everything is gone, and no one can help you at all.