Framerate

I play Counter-Strike 1.6 and i used to get a steady 30 frame rate per second. However recently, my frame rate became very volatile, jumping from 60 to 9 to 38 to 4. I tried to turn vertical sync off but to no avail. Can someone tell me how to get a steady frame rate?

Windows Xp home edition
768 ram pc2700
2.7 ghz celeron
intel extreme graphics controller 82845g

Thats most likely some software that runs in the background eating up all your CPU power.

I would recommend a thorough check for spyware/trojans/worms etc…