Question : Problem: Fan seems not to work AND cpu runs at 100% after about ten minutes

Originally, my system worked perfectly.

Maybe a year ago, I noticed that Internet Explorer was malfunctioning.  I tried downloading and reinstalling a new copy, but that didn't help.  So I downloaded Firefox and I've used that ever since, having given up on figuring out what was wrong with Internet Explorer.

Shortly thereafter, Windows Media Player stopped working.  When I try to use it, I get this error message: "An internal application error has occurred."  So I've been making do with Windows Movie Maker in the meantime.

For a few months now, I've noticed that I can't run programs that used to run fine on my computer.  For instance, I have Warcraft III, which once ran perfectly.  However, now almost from the moment it begins running the mouse is jumping around and the cpu is running full bore at 100%.  Even after I close it, the cpu is still running at 100% even for programs as simple as notepad or solitaire.  Same holds true for World of Warcraft.  I haven't used either in some time, and yet I'm starting to have similar problems with other non-game programs as well, including Firefox.

I've run multiple virus scans, finding nothing.  I've done registry fixes and defragged the computer (today it tells me that it can't defrag the computer because some portion of the disk can't be defragged... or words to that effect).

I had come to the conclusion that I should just reformat the drive and reinstall my OS and everything else.  I got the disks from Dell.  I even bought new memory cards (I only had 512M before and now I've got 2 one Gig memory cards installed).  I spent the last two nights backing up almost everything on my computer and uninstalling every non-essential program.  I was about to try reformatting the drive when I decided to try something else.

Last night I booted up the computer in diagnostic mode and ran a couple tests.  I found that my processor fan was apparently not working.  Where the system was expecting 5000 RPM on high it was getting 0.  I looked carefully and felt for any breeze coming from my processor fan and I'm pretty sure it's not functioning at all.  I ran the test again this morning with the same result.  I was about to order a replacement fan online, when it occurred to me that for all I know the fan could be fine and some other problem could be preventing it from functioning... so I decided to consult some experts.

Could excessive heat in the system and processor cause all these problems I've been having?  Could it be that such heat has caused permanent damage to the system or processor such that even getting the fan to work again will not be sufficient to get my system working as it once did?  Are there any other tests I can do to see if the problem could be something other than the fan hardware itself BEFORE I buy a new fan?

Thanks.

-Mark

Answer : Problem: Fan seems not to work AND cpu runs at 100% after about ten minutes

Have you opened the case to verify the fan isn't running?  If it isn't running, turn the computer off before you do fry that cpu.  

Do not run  a memory test or a hard drive test until that fan is running.  If it is running and the cpu still bogs down at 10 minutes, we can look at other sources, but if the cpu fan or any fan in your system is not running and you do not have special software that is controlling your fans, then you should do everything to get your fans running before you do any more troubleshooting.

Overheating your cpu can definitely do more damage to your hardware then a virus/malware which it sounds like you might also have, but let's get your hardware working properly first.

RID is correct, that typical CPU overheating shows up as sudden shutdowns, but once you get to that point, some real damage has probably already occurred.