MAJOR UPDATE:
I have two logons on my computer, one for me and one for my wife. The fan thing is ONLY happening on MINE! What the heck? When I log in under her, it doesn't happen AT ALL. The fan will turn on if I open, say, Word on her logon, but only for a couple seconds, then turns off. As soon I logon under MY ACCOUNT, the fan starts up and does it as described above. If I'm logged in as me, then SWITCH to her account (without logging out of mine), when I'm on her account it STILL DOESN'T do it. Some more info:
1. I have my Windows XP "look" set up differently than hers.
1a. I also have my own personal start-up, shut-down, and error sounds that I use. Hers are the standard. I dont think that would matter?
1b. I tweaked my settings on my XP look by using this guide:
http://www.tweakguides.com/TGTC.html
...but I don't think any of the settings I changed would cause the fan thing (I only changed things that you can do by selecting or unselecting something in a menu, I did not manually change any registry keys or anything). However, I'm going to go through the entire list and make a list of the things I did change and post that here once I have it.
1c. I have a password for my logon. She does not. But both accounts are Administrator (because certain older programs won't work right if they're not, like Photoshop version I have).
2. I have installed a number of free programs having to do with dvd burning, ripping, shrinking, and XviD conversion. I researched to make sure all programs were spyware free. These programs are: AutoGK, DVD Decrypter, DVD Shrink, ImgBurn, pgcedit, RipIt4Me, and VobBlanker. Some of these show up in the "Show All Programs" menu on her logon, and some don't (see #3 below for more details). I also downloaded MPEG4Modifer and DVDFabDecripter, but never installed them.
2a. I also downloaded and installed Firefox, AVG Free, and ZoneAlarm Free.
2b. I have FireFTP on my Firefox, but not on hers.
3. Our "Show All Programs" menu has slightly different stuff on it. But I think that's because I probably deleted some stuff off of hers and added some stuff to mine. I had some weird issues when trying to delete stuff or add stuff to this menu. Sometimes it would add a folder to the top where Windows Update is at, even though I dropped it down below. And sometimes when I'd delete something from hers, it would say it would affect all users, and sometimes it didn't say that (which may be why I ended up leaving some stuff on hers I'd normally take out, like the DVD ripping stuff). Screen caps below.
"Programs" is hers and "Programs2" is mine. I'm not sure where the Xvid folder came from on mine, but I'm guessing it was part of AutoGK.
4. Early on, I had an issue where I had my logon on and switched to hers and had hers on, with a program open on each, and when I tried to switch back to mine, it kind of froze. It went extremely slow, was hanging on a black screen, and I waited like 5 minutes and nothing was happening. But the hard drive light was going on and off during that time. I eventually just held down the power button long enough to shut the whole thing down. Now, if the hard drive light happened to have been on when it actually shut down, I'm not sure. And I'm not sure if this could have caused some kind of problem...
5. Something else weird, on my logon, when I right-click and get properties, and go to the settings tab and then choose advance, when I click either okay or cancel, and also when I click okay or cancel to close the main properties window, I can HEAR a little "sfftt" noise coming from the computer if I put my ear close. When I do this on her logon, I do not hear this noise. (???)
So any thoughts so far as to why this would only be doing this on my logon? Could I have some kind of spyware or infection only on my logon? I'm not sure how I would have gotten that, as I don't think I went to any site that would download that, nor have I got any emails from people I don't know that I opened (and emails from someone with a virus, etc.).