SBS 2011 Essentials -- Backup is set to backup C: and D: every night. Once in a while, the backup status is listed as "Incomplete", and when I click on "View Details", it shows "System Reserved" and "Operating System" as "Successful", but "D:" as "Unsuccessful". Sometimes it will succeed for 6 or 7 days in a row, then fail for a day, work for 2 days, fail for 2 days... no real pattern.
I’ve tried to look at the backup logs but they are very long and very cryptic, so I’m not sure what to look for. I could post a log file here if someone knows how to decode these… but I’m open to other ideas.