ATI Radeon HD 3650 locking up?

I've tried using every driver I can possibly find for this card and nothing fixes it! I mainly got it to play City of Heroes with and it works great, but after about a hour of my computer being on, in or out of the game, it locks up and nothing will respond anymore. Any ideas? I upgraded from a Radeon 9800 AiW, and yes, it's an AGP slot on a XP OS.