I'm running Win7 on my dev system, and I've scheduled disk defragmenter to run every Tuesday at 1am.
I leave my system running, Monday night. It does not matter if I just lock the system, or if I log off, or if I reboot - disk defrag does NOT run. The screen for DD will indicate that the last time it ran was when I ran it manually, after the last time the scheduled DD did not run.
What could be preventing the scheduled DD from running? I've got the checkbox ticked for "Run even if not logged on."