Strange CPU usage problem

[Acesover8s]

I'm not computer illiterate, but this one has thrown me for a loop. My computers performance has dropped dramatically in the last week.

While idling, the CPU Usage History alternates every second between 2% and 92%. I have run every anti-virus software, adaware, hijack this, all come up with nothing.

I have recently added a secocnd monitor to the 2 monitor video card that was already there, but it ran fine for a few days, and then blammo.

The sound from my onboard sound card has also fizzled and everything sounds garbled and slow.

Any thoughts?