If you are on a fresh install do you have any service packs installed? Try SP2, but install SP1 first and see if it works.
Also can you launch libra then your game, tab out, open a picture in paint copy a piece of the picture or the whole thing and then tab back in game and wait for it to take a screen shot and see if its pasting the copy picture instead of a screen shot. I have a similar problem to you as my libra takes the last item on my clip board.
If it does then it might be a computability issue with vista or a certain windows kb update.