Thanks, I'm running 10.8.3 on a MacBook Pro. Isn't that the system (10.
that SnoozeMaster was designed to work with??...
Yes. Starting with 10.8, Apple introduced a new interface (EventKit) for developers to add/edit/remove/monitor events, alarms, reminders, etc.
SnoozeMaster uses that interface to do everything it does. Unfortunately, when EventKit misbehaves, so does SnoozeMaster.
We've identified a few limitations with EventKit (it won't allow editing events from calendar invitations or delegate calendars, for example), and also a few bugs. We've reported them to Apple. It's frustrating for us too, but its all we can do. We'll see if 10.9 addresses any of those issues.
I'm glad after a reboot SnoozeMaster started working properly again for you.