Some essential information is missing: in the Processes tab of Task Manager, see what processes are responsible for this huge CPU load.
It's likely 'something' changed. If you can't find out what it was and how to undo it, the brute-force attack is to try a system restore back to, say, 2 weeks ago. But maybe a more specific diagnosis and treatment is possible.
Well starting last week my computer has been really slow, it will take about 2-3 min to load windows into the log in screen. Then when I log off or switch users, the sound windows plays will studder (same for when logging in). I can't even watch videos online because it will start studdering/lagging and being really slow. I have done virus scans and spy/ad ware scans, and they came up with pretty much nothing. This is a fairly new install of windows XP as our last hard drive died not long ago. Under windows task manager, when I am doing nothing but web browsing/msn and as I am typing this, my CPU is hovering around 50% jumping up to over 80% at times and more then half of my 1gb of ram is being used.
Can anyone help!!! It is getting to be a pain to use this computer!