Sudden drop in framerates

I'm having a very odd problem with FS9. No matter what my graphics settings are my framerates stay below 7FPS! The problem just started this monday, before Monday I was getting constant framerates above 18FPs with all sliders (except mip mapping and 3D clouds) maxed. I've tried everything I know how to do, nothing helps! The odd thing is that I installed Windows XP SP2 on Sunday but I don't have the firewall or automatic updates running so I have a hard time believing it is SP2. Please help me out here!
System Specs:
P4 2.0GHz
1Gb PC2700RAM
GeForce FX5200 (256mb) @ AGP4x
36.7Gb ULTRA 320 SCSI C: Drive
40Gb ATA100 D: Drive
System Specs:
P4 2.0GHz
1Gb PC2700RAM
GeForce FX5200 (256mb) @ AGP4x
36.7Gb ULTRA 320 SCSI C: Drive
40Gb ATA100 D: Drive