My CPU Usage keeps going to 100% after i use my pc for a while, i don't know what is happening. i can't even shut down because its soo slow. so i have to pull the plug out to restart the pc. pathetic.

Can you see on the Processes tab on the Task Manager what process is running the CPU up to 100%?

Task Manager: Ctrl > Shift > Esc

Or: (for more detail (in Pro)) Look at Start > Admin Tools > Performance

Or: look in your event viewer: rt. click My Computer then click Manage then Event Viewer.
open the system as well as the application tabs & look for X errors. click error line for details. post back the source & event id especially of errors that seem to coincide with a surge & or shutdown.

Application

Source: EventSystem
Event Id: 4609

Source: VSS
Event Id: 8193

Source: AVG7
Event Id: 100

Source: MsiInstaller
Event Id: 11706

Source: Messenger
Event Id: 1000

System

Source: DCOM
Event Id: 10005

Source: Service Control Manager
Event Id: 7001

Source: W32Time
Event Id: 29

Source: SideBySide
Event Id: 59 / 32

Did you check the Task Manager?

Those Event Errors don't lead to much besides possible AVG7 problems
& a corrupted installation of .NET Framework & COM+.

Perhaps see if turning off AVG changes things.

You can see details from those "Events" here:
http://www.eventid.net/search.asp