Last night, for some reason, 50% of my CPU was being used by something I couldn't see. I use the Yahoo Widgets app and it showed that whenever I had another programme open about 93% of the CPU was being used.
I checked with Process Explorer and it said that "Hardware Interrupts" was using 50% of the CPU. I searched it and some places say it's the graphics drivers and the card is fried, some say I have to reformat and that it's a Windows deal.
I noticed that it only really seems to affect the performance when I'm burning or ripping a DVD.
try using hijack this and posting it on this forum (maybe dmo will know) or posting it on one of those specific techie websites that have specific forum sections to take a look at your processes and whatnot