The other day my dad's comp got a blue screen and had to be shut down. Upon restarting it is now very very slow and the CPU Usage reads at 100% almost all the time. By slow I mean it takes litteraly 2 min for any program to open. And during that time there is no hard drive chatter at all. I'll click to open a program, the comp seems as if it's doing nothing, then 2 min later the program pops open. And forget trying to open 2 apps at once. The comp all but almost freezes at that point. I checked the processes list and it says NOTHING is using the cpu. But then I'll immediately switch over to the Performance tab and it reads 100%. I've run every spyware/virus checker I could find but the comp is still slowed. And System Restore won't let me revert to an earlier point. (piece of garbage) The comp runs smooth as silk when in Safe Mode.

Uninstall your video driver and using XP's native display driver see if there is any changes. The Secret Letter From Iraq

How old is this computer. If its not something running in the background that’s taking the cpu time. Sometimes when a harddrive is beginning to go it will be slow to read and write to disk. It could be something that XP is doing as well. There might be a piece of hardware that XP is trying to configure. If its running at 100 percent for long periods....I would guess you got something or someone accessing the CPU. You will just have to look around to find what it is.

We can tell it's software related, question is what software. Is this computer on dial up if so it could be a microsoft updates. Try eliminating items in the add/remove programs and/or looking in your msconfig startup items for odd looking items. If still nothing then go into your services and stop some items that you know you do not need (example: telnet) "The three most dangerous things in the world are a programmer with a soldering iron, a hardware type with a software patch and a user with an idea."

There is a known virus/trojan that does this when a PC is infected. You don't mention witch process is using upp 100% of CPU. (Taskmanager / processes) Of course you checked that you didn't loose part of your memory at the time of crach !?

I'm at work right now so I'll try all this when I get home. Waxinator, that's the weird part. All of my processes are reading 0 (besides System Idle) But under the Performance tab it's reading my cpu as going 100%