G'day Dennis;
This explanation thanks to Alan in the spyware.general forum:
Likely you are using a 24-hour clock. The current
version has issues when using a 24-hour clock.
Follow these steps:
1. Go to Start > Settings > Control Panel > Regional and
Language Options.
2. Press the Customize button.
3. Click the Time tab.
4. Set the time to a 12-hour setting (leading letter(s)
is/are h) and press Apply.
5. Now go and set the scanning time to whatever you want
in MSAS and press the Update Schedule button.
6. Change the settings back to 24-hour and press OK.
7. Redo steps 1-6 each tie you want to change the scan
time once you have completed step 6 and want to
change the scan time to another time.
This issue might be corrected when Beta 2 is released
later this year, but don't count on it. This is because
the product must be localized for each region of the
globe and they are currently working on an English
version. When the product goes final this issue will
definately be fixed.