This is a strange problem that i've been Googling for months with no success. I'm still not sure if this is completely a hardware or software issue.
I have a Dell Inspiron 6400 Laptop. I keep Windows XP for games and Reason, and until several months ago, i was using FC8 for everything else. Everything was working fine; i never once encountered this problem. I upgraded to FC9 using Upgrade (which i hear is not a great thing to do) and the operation went successfully after a few initial hangups. However, whenever i'm using a significant amount of RAM and/or CPU and/or GPU, the fan starts up, the CPU usage total jumps up to 100% and stays solid for a good 5-15 minutes, and everything becomes so slow it's utterly unusable.
Here are the things that have me stumped...
First, the CPU usages of all running programs do not add up to anywhere near 100%. Firefox might be at the top with maybe 30%, or maybe xorg. But there are no processes that seem to account for the CPU usage reading.
Second, although the CPU and GPU are warm, their temperatures never reach anything 'critical.' The highest i've seen them is 130F or about 54C, and that's happened maybe once. Usually it tops out at a few degrees F less. So, those don't seem to be overheating, but the fan continues to run solid until the lag-fest is over, and it only seems to happen during high GPU or RAM usage (though i have 1.5 GiB and have never seem my memory usage exceed much more than 60%).
Third, this never happened before FC9, and it still doesn't happen in XP even after playing World of Warcraft for hours on end, but after watching a few Flash videos, or playing a mildly graphics-intensive game like Gish, or having a lot of tabs open in Firefox, i hear the fan kick on and everything almost freezes. The GPU seems to be the most functional during this lag, but that's probably to be expected considering GPU design. If i kill the power and reboot, it's still laggy while booting, but by the time it's finished booting, everything is about back to normal.
This all makes it sound like a hardware issue, but my friend said he had the same problem when he installed FC9 (fresh), and he solved it by re-installing FC9. I would try this, except i don't want to go through the time-consuming process of installing all the programs i use and hand-configuring my system to a state i consider perfection.
If anyone has any suggestions or information, i'd be greatly appreciative. This problem has had me stumped for awhile now and i'm really getting tired of dealing with it.