Different balances Bitcoin-Qt vs. Blockchain.info Why is the balance in my Bitcoin-Qt wallet different from the balance when I check the information about my address on blockchain.info? All transactions are confirmed.
The problem is likely that in Bitcoin-Qt, your balance is not kept in a single address. For privacy reasons (of the system as a whole), change from transactions is sent to new addresses.

The abstraction provided by the Bitcoin-Qt client is that of a wallet, in which coins enter via (don't reside at) addresses, and are sent out from it, and is otherwise a black box. When you look at it via blockchain.info or similar sites, you get a more low-level via, where "balances" are kept per address (which is actually sort-of misleading, as at the protocol level, Bitcoin doesn't work in function of addresses or balances at all, but in terms of transactions on individual coins).