Sudden FPS issue

[Stealth1304]

My desktop can run this game fine until it all of a sudden for no reason at all it drops below 1 FPS and it can last anywhere between a few seconds and 30 mins until I quit and restart the game. My laptop can run this game on the default settings for medium with no problem.

What I have done.
1. set settings to the ABSOLUTE minimum
2. restart the game EVERY time I die or land
3. deleted the game cashe file EVERY time I restart the game
4. went into msconfig and remove all unnecessary programs at start up and restarted

NONE OF THIS HELPS!

Custom Desktop

Operating System: Windows 7 Professional 64 bit
Processor: AMD Phenom 9600 2.3GHz Socket AM2+ 95W Quad-Core Processor
Motherboard: ASRock A780GXE/128M ATX AMD Motherboard
Memory: 4 x 1GB DDR2 800
Graphics Card: HIS HD 4870 IceQ 4+ Turbo 512MB (256bit) GDDR5 PCIe
Hard Drive: SAMSUNG Spinpoint F1 750GB 3.5" SATA 3.0Gb/s Hard Drive 7200 RPM
Power Supply: COOLMAX NW-650B 650W Power Supply
Monitor: 20 inch screen with 1600x900 resolution and 19 inch screen with 1440x900 resolution

HP dv6tse Laptop

Operating System: Windows 7 Home Premium 64 bit
Processor: Intel Core i5 450M 2.4 GHz Dual-Core Processor
Memory: 6GB DDR3
Graphics Card: ATI 5650M 1GB
Hard Drive: 500 GB 7200 RPM
Monitor: 15 inch screen with 1366x768 resolution