Losing Bitcoins from Bitcoin-Qt wallet

[rubyoak]

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/1BvHrxNdPdzfUAu9YH9QmwRYoJf5YGuWrN
not 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. I 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.

[1714993346]

1714993346

[BunsenBurner]

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/1BvHrxNdPdzfUAu9YH9QmwRYoJf5YGuWrN
not 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/Change

I 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_directory

If 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.

[deepceleron]

Another good reason not to use the "official" wallet IMHO.

Don't be silly. The answer:

However when i checked blockchain.info

There's your problem. Don't look at that site.

[ksteve96]

Did you run combofix or anything similar?  Combofix will delete your wallet but it will save a copy somewhere.  This actually happened to me with over 100 BTC but after I got done panicking I found it in some directory combofix makes on the root of the drive.

How long did you have bitcoin-qt closed? Half a day to dl the rest of the chain could be normal for 5 days if you have a slow or restricted connection, but that doesn't seem right either.  Sounds like the whole data directory was deleted.

When you open bitcoin-qt ( not "opened my wallet" like you said, the wallet and client are 2 separate things), is the receiving address 1BvHrxNdPdzfUAu9YH9QmwRYoJf5YGuWrN still there or is it gone?  If it is gone then you are opening a new wallet therefore will not be seeing your coin.
If this is the case you need to think about how or why the contents of the data directory got deleted. 
On W7 it would be C:/users/*your user name/roaming/bitcoin/

If it was deleted, you may still be able to recover it with a recovery tool if it hasn't been overwritten too much. If you think or know that it was deleted, I recommend using a live USB recovery tool to search for it otherwise you risk overwriting it more when using the hard drive. 

[rubyoak]

I discovered my problem and recovered my bitcoins! I initially installed Bitcoin-Qt under my user (no admin privilege) login. The installation had an error that lead me to believe that I needed admin privilege. I logged in as administrator and installed without problems and then transferred my bitcoins and logged out.
I later logged back in as user, and this user account had a short cut to Bitcoin-Qt from the bad installation. Forgetting that I had installed under a different administrator account, I clicked the Bitcoin-Qt, it started and when it finally synchronized it had also created a new wallet address. My original wallet address was still under my administrator login.
I didn't realize my problem because I rarely login as administrator and when I investigated the block chain it looked suspicious to me. When I did finally login as administrator, I realized my problem.
Thanks for all the good responses and information. No files had been deleted and my wallet was not compromised and nothing lost.
I do believe there are installation issues however. If the user needs admin priv, it should pop up and ask the user to login as administrator.
Also, as a test, I tried installing under a third non-admin account that also failed. And with this failure, somehow I now have error messages with the Bitcoin-Qt under my administrator account. I don't believe files are properly separated between users.
I believe I am going to uninstall completely and only install one version again under administrator.

[deepceleron]

I discovered my problem and recovered my bitcoins! I initially installed Bitcoin-Qt under my user (no admin privilege) login. The installation had an error that lead me to believe that I needed admin privilege. I logged in as administrator and installed without problems and then transferred my bitcoins and logged out.
I later logged back in as user, and this user account had a short cut to Bitcoin-Qt from the bad installation. Forgetting that I had installed under a different administrator account, I clicked the Bitcoin-Qt, it started and when it finally synchronized it had also created a new wallet address. My original wallet address was still under my administrator login.
I didn't realize my problem because I rarely login as administrator and when I investigated the block chain it looked suspicious to me. When I did finally login as administrator, I realized my problem.
Thanks for all the good responses and information. No files had been deleted and my wallet was not compromised and nothing lost.
I do believe there are installation issues however. If the user needs admin priv, it should pop up and ask the user to login as administrator.
Also, as a test, I tried installing under a third non-admin account that also failed. And with this failure, somehow I now have error messages with the Bitcoin-Qt under my administrator account. I don't believe files are properly separated between users.
I believe I am going to uninstall completely and only install one version again under administrator.

Each user that runs Bitcoin will have their own wallet.dat and copy of the blockchain. This is separate from the program installation.

An administrator can install Bitcoin on a computer where users are not allowed to install software. Then any user can run Bitcoin. The Bitcoin data directory has a shortcut on Windows, %APPDATA%\Bitcoin, that is user-specific.

[bitpop]

Unknown address is your new 'change'address