ZASS 10.0.246.0. Win Vista and Win 7

I have a weekly scan scheduled for Saturday nights at 1:30AM. However, I find it running scans seemingly at random. Certainly not at 1:30AM and not even on Saturdays.

Some of the scans take forever. Yesterday morning (Friday) I found that it was running a scan that had been running for over 48 hours on one of the Vista computers. Right now (12:41PM) there is a scan running on this computer that has been running for just under 3 hours. I did reboot the computer about 3 hours ago, but why is this POS running a 3 hour long scan after a reboot?

Why all the scans? Why are they running at times other than I scheduled them? How do I make them stop so that I can actually use my computers?

Thanks
Jon