This scan (if you can get online) will show what's inside:
http://www.belarc.com/free_download.html
Is this a new problem? Were things working OK previously? Any new hardware and or software?
If both XP (hard drive) and Knoppix (CD drive) are affected like this I would guess a heat issue.
A case fan blowing in or out would not be all that big of a deal although in general front fans intake and rear fans exhaust.
There are also fans on the PSU and the CPU and perhaps the Graphics Card.
You can run with the case open and observe the behavior. Just generally feeling the air for heat shifts.
Changing the thermal grease between the CPU and the heat sink might help if it is a CPU issue.