As far as AVG, don't think you can disable it. I think you just have to shut it down completely. However, AVG gets along very well with the online virus scans and even most of the other antivirus programs, so this shouldn't be anything you even have to concern yourself with.
For the Windows error on startup, it seems that may be an HP issue. Check the info here.
http://blogs.msdn.co.../29/497983.aspx
Did you have Norton installed at one time?