PagingPro scheduled tasks not running

I have a school bell schedule set up as a Calendar and scheduled through Paging Pro. It has been working without a problem, until today - this morning it was not playing scheduled pages. It was working without a problem last week and I have not made any system changes since then (I'm the only system admin). Please advise what logs I can submit to help diagnose this issue. The same thing happened Monday after changing the clocks out of Daylight Saving Time but it worked fine on that Tuesday.