Hi Pop,
This is a quick one, as I'm off out, but..
1. Have you got SP2 loaded
and 2. Can you find a folder called
TV Media
Alarm bells rang when you said you had some video editing software newly installed.
TV Media is known to cause conflict problems with startup/shutdown with SP2.
Late for work now, I'll supply more detail later, if needed...
Cheers
Liam