I just purchased an ATI Radeon Sapphire 2600 HD Pro 512 MB AGP 4x/8x and installed it. Since I've gotten it, I've had multiple issues with restarting. Whenever I try to run Call of Duty 1, 2, or 4 on a different resolution than my screen is set at, the screen goes black and my computer immediately restarts. It's also restarted multiple times from enabling my dual monitors, and from changing the screen resolution at all. I've installed the latest Catalyst drivers and everything, and I can't figure out what is happening. Any help is extremely appreciated.
CPU: HP Pavilion a1007w, AMD Athlon 3200+, 2.21 GHz
Video Card: ATI Radeon Sapphire 2600 HD Pro 512 MB AGP 4x/8x
RAM: 2x512MB (1GB) DDR SDRAM
Monitors: Samsung SyncMaster 220WM (Digital), Gateway FPD1730 (Analog)
HDD: Western Digital 200GB, Maxtor 80GB