hmmm sounds a bit like the Blaster virus.
You'll need to run the Blaster worm remover (click here) then do the following:
Click Start, and then click Run. (The Run dialog box appears.) Type regedit Then click OK. (The Registry Editor opens.) Navigate to the key: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run In the right pane, delete the value: windows auto update Exit the Registry Editor.