I've been having some problems with my computer recently. I ran the System Configuration Utility (msconfig) and selected "Diagnostic Startup" from the "General" tab. It said I needed to restart the computer for the changes to take effect, so I did. After restarting the computer, a message box came up saying that the hardware configuration had "changed significantly", so I needed to reactivate Windows XP in 3 days. (I hadn't installed any new hardware or anything, either.) When I chose to "Reactivate now", the message box just went away and nothing happened. When I selected "Activate Windows" from the start menu, I got an error message: I've already scanned for viruses with AVG and for spyware with Ad Aware. What do I do now?