Scheduled Scan Wakes Up Computer When No Scan is Scheduled

Using Avast 6 free on XP SP3…

I have full scan scheduled to run weekly on Mon, Wed, Fri, and Sat on a computer that I leave in standby mode all the time. It seems that Avast is waking up the computer at the time of the scheduled scans even on Tues, Thurs, and Sun. I know this because I run a program on this computer called WakeOnStandby which, among other things, keeps a log of wakeup events. From this I can see the time that the computer wakes up and it is just prior to the scheduled scan time. I have tried changing the time of the scheduled scan from 8 pm to 9 pm and the time the computer wakes up changes in lock-step.

Even though it seems that Avast is waking up the computer, the scan log shows that no scan was performed. It almost seems like Avast is waking up at the appointed time every day only to see that nothing is scheduled to be done. Because Avast uses it own scheduler, it is hard to know exactly what is going on. I wouldn’t mind all of this except that the computer does not go back to sleep after this. So the point of keeping the computer in lower power mode is being defeated.

So what is the problem here? Thanks