Specs: Windows XP Pro w/SP1; 1.5 Gig of Ram; AMD 3000 XP; 60 GB HDD.

Problem: Recently my computer started to run EXTREMELY slow. So I ran the usual virus scanner, adware, spybot, registry checker, and even defragemented, but I still couldn't fix the problem. When I press ctr-alt-del and under processes it shows that explorer.exe is using 99% of CPU usuge. Well since explorer is sucking my CPU I cant open any application because they take long periods of time to open as my CPU is for some odd reason devoting all its power to explorer. So anyway I click end process of explorer.exe; my icons go away etc but I am able to run programs and things at my normal speeds. But on occasion if I have more than one program up, the same thing happens of my CPU devoting all its usuge to one application, causing the others to "not respond". I know the best thing would be reformat, But I really hate doing that for every little problem I encounter. Any Ideas What's going on? Is my HDD integrity messed up? Windows corrupted?

You need to install SP2. It squashed that bug.

Look here...
MSKB Search Results: Explorer.exe Process Uses Many CPU Cycles When Windows Is Idle

Thank you so much! Will do asap, you saved me from reformatting!