Just another tip: Richard's solution didn't work for me but then I opened up Edit->Preferences->Calendars and Tasks->Alarms and unchecked and rechecked my calendars. All of my queued up alarms popped up at that point and now all of my alarms work fine.
Just another tip: Richard's solution didn't work for me but then I opened up Edit->Preferenc es->Calendars and Tasks->Alarms and unchecked and rechecked my calendars. All of my queued up alarms popped up at that point and now all of my alarms work fine.