Vista - Cannot run games from vista's game explorer

I'm a new user here as in I just registered, but I've been around the forums for a while here watching various threads and learning various things from the forum.

I'm not sure of where should I post this thread, so I just posted it in gaming since it is about gaming well, here it goes...

Anyway; I have a vista ultimate x64 machine, I built it on my own for gaming specifically. It's about a year old now.

Everything runs smooth and without any problem in my copy of vista, Except the game explorer. I really liked and I thought it's very useful, especially for me, a gamer.

Whenever I try to run a game via the game explorer, I get this error;-

http://i33.tinypic.com/250qp01.png

although I can run the games normally from their directory or from a shortcut on the desktop.

Thanks..