This is a recent problem on a server that has been in service reliably for 6 years. More than 12 months ago it was virtualized (P2V) onto the Hyper-V platform and remained reliable.
About 2 months ago we started having problems with Scheduled Tasks not running, and failing with the familiar error "0x8007052e: Logon failure: unknown user name or bad password" shown in the task scheduler log.
This ONLY occurs after a reboot, and we must re-enter the password of the user account under which the tasks run. Then it is fine until the next reboot.
I have seen MS KB http://support.microsoft.com/?scid=843281
which refers to a hotfix, but the version of mstask.dll shown in the hotfix is 4.71.2195.6940 and ours is newer, 4.71.2195.6972.
Previously I also tried deleting the sa.dat file and recreating the scheduled tasks (per another MS KB) but that didn't help either.
There have been no changes to the system config, no new software, nothing, except for monthly Windows Updates.
After browsing the MS KB and a lot of googling, I'm stumped. Anyone have a clue where else to look, or what the problem might be?
If it isn't this, the stored password for the task may not actually match the current password of that user, so this is something to check as well.