Is it 32 bit or 64 bit computer? What is the service pack installed? You may restart your computer in safe mode and try to change schedule scan setting and turn it on. Restart the computer to normal mode and let me know if it fixed the issue with schedule scan..
Vista 32 bit with all updates and service packs installed.
Strangely, not long after I posted the scan began. However, there is still a mystery. It was scheduled for 1:00pm, (computer and local time), and didn't start until around 2:30pm.
All very odd, because on my other, (Win 7) boxes the scheduled scan always starts on timer.
Could it be perhaps an issue that there was a lot of foreground activity allowing no opportunity for the background scan t started?