Well, I am somehow left with all those wallet.dat files that turned into a ".bak" file. Reading through those threads dealing with that exact problem, the coins are very likely lost. Really an odd problem as it never happened to me before. Some people say that it happens when you create a copy of your wallet.dat while the client is running... I have no clue, I just know that my coins are gone >.<
So you did not copy your Wallet.dat to a backup location? You should always store a copy of your Wallet.dat in a safe location (like a USB stick)