You may see the following error in the Windows Task Scheduler, or in various places in SyncBackFree/SE/Pro which 'drill down' to the Scheduler.
"0x8004130F (or 8004130F): No account information could be found in the Task Scheduler security database for the task indicated"
which means that your Windows Task Scheduler is generating an error (and not running SyncBackFree/Lite/SE/Pro when it should). The error is a Windows error in the Task Scheduler and not in our software
If you are using an OS earlier than Vista, you may want to try a trick that some users have reported sometimes helps, which is to delete all Scheduled Tasks in the Windows Scheduler, reboot at least once (very important) then try re-creating the Tasks (re-Scheduling the profiles). The theory is that this deletes (during that very important reboot, which you must not omit) the apparently corrupt security database used by the Windows Task Scheduler as 'no longer required' and that re-creating the Tasks creates a new security database (hopefully not corrupt). It is not really feasible to use this workaround with the new Task Scheduler in Vista and later, as MS (and maybe other applications) have leveraged this for lots of system/housekeeping tasks, and it is probably not feasible to replace them all.
We cannot guarantee the workaround will help, and it is provided 'as is', without prejudice.