Hoo-boy, it isn't just me!
Yes, I had (yes, had) this problem, and it came from a variety of sources.
Three things to check:
1. Install MP2. Immediately.
2. If you are using a frequency-based schedule, and you want the backup to run once per day, make the frequency "1 day", not anything less. I had everything set to 9 hours (1 hour more than the 8-hour window), and had tons of trouble. Resetting them all to 1 day fixed it. Mostly.
3. Sometimes, for some reason, the file "pempersist" (which allegedly tracks active jobs) will get wonky, and NetBackup will think certain jobs are active when they really aren't. In this case, the Polciy Execution Manager (pem) won't schedule the job for another run. In this case, do this:
a) Make sure you have no jobs running
b) Stop all NetBackup services (or just run bpdown)
c) Find the file "pempersist" in the NetBackup\bin\bpsched.d\ directory, and rename it (pempersist.old, for example)
d) Restart NetBackup services (run bpup)
(Note: I still have an open case with Symantec on the pempersist issue; there may be more information forthcoming.)
Good luck!