BE 2010 R3: Loses schedule in the backup job randomly?

Twice now I have had it where I have set a schedule for the backup job and at some random point perhps a copule weeks later, the schedule just disappears.  We only find out because the backup didn't run the night before.  Looking at the job setup, It was set back to Run Now. 

Has ayone seen this?  Anything in particular I should I look for in the Server 2008 R2 event logs? 

Thank you.