Still doesn't work, and someone already suggested xna and direct x before and it didn't fix it, im pretty sure I mentioned that.
Considering, during a PM to me (which I said, continue the conversation here) - you said you had the latest version of XNA and .NET
Which will fail, as I know the version of XNA we use for the launcher is 2.0, and the .NET is something else (Can someone check their install, Im not at the main computer at the moment).
I believe thats the source of your problem.