AnyDVD will always scan the disc right when you put it in. If you don't want AnyDVD doing this when you boot your system then, honestly, remove discs before rebooting or booting.

To get PowerDVD to not automatically play discs make sure in the settings that it doesn't autoplay inserted discs. There is a setting in PowerDVD 8 to start PowerDVD when Windows starts and another setting to automatically play a disc when it's inserted. These settings likely also exist in PowerDVD 7 and prior versions.

My advice is to (1) not leave discs in your drive(s) and (2) disable PowerDVD from starting with Windows and from automatically playing inserted discs.