My sister's computer initially was infected with hundreds of virus and only would show Windows backgroud (no icons or start menu). I ran antivirus and cleaned them up but cpu 100% still. After trying several suggestions on internet, I decided to format and load fresh copy of Windows but still 100% and very slow. so I let all the MS updates install and now up to SP3 but still 100% CPU. Everytime I run task Manager, taskmgr is the highest running process. This also occurrs with Process Explorer. I ran diags on Motherboard, HD, memory, video card, etc. and all passed. I also attempted to run in Safe Mode but the Mouse does not work in Safe Mode (maybe even the keyboard because ctl-alt-del does nothing. I am at my wits end with this computer. Does anyone have any suggestions? it is a Dell Dimension 2400.