Either you have a problem that is stumping everyone, or because it is Christmas, nobody's had the time to answer you. I'm not sure how to solve this problem myself, but this is what I would do if it happened to me.
I suspect that if you were to go to your folder at C:\Documents and Settings\(Your User Name)\Local Settings\Temp, you would find that there are a lot of .tmp files and maybe even one or more .exe files, and if you do find any .exe files, then they are probably working in the Task Manager. (To see this folder, you have to open Folder Options and click on "Display the contents of system folders" and "Show hidden files and folders". Then uncheck "Hide extensions for known file types" and "Hide protected operating system files. (Recommended)")
First, since I am a backup fanatic, I would use my latest backup to restore everything in its perfect form again. However, it sounds like that is not an option with you. In that case, I would use System Restore to go as far back as I could, hoping that whatever has caused such a problem would disappear from that.
The next thing I would do is to clear out my temporary files and my temporary Internet files and cookies. Rather than to re-write everything again, I will refer you to where I have written those instructions for someone else. http://forums.cnet.com/5208-6142_102-0.html?forumID=5&threadID=274178&messageID=2645258&tag=mcnt. (If that doesn't take you directly to my post, it's post 4 of 6--and then read post 6 of 6 too.)
I forgot in that post to mention that in both of the Temp folders, there should be one file that you cannot delete because it is active. In the user settings temp folder it is a .tmp file and in the Windows\Temp folder it is one that would be called something like Perflib_Perfdata_700.dat. If you have any more than one, then delete as many as you can, re-boot, and then try again.
Try this and see if it does anything. I can't hurt, and would only result in a cleaner PC. If you still have the same problem, then come back and make another post to ask for more help. I hope it works for you.
The breaker (no surge protect) that my desktop is on was tripped the other day. Computer would not re-start until following day. Now, sound and USB do not work and machine (XP) is running really, really slowly. Ran AVG and Spybot. Task mgr. shows SYSTEM using 100%. Will it help to re-load operating system, get new motherboard, or is this Gateway now junk? Need recommendation.