I config my backup to include the automatic backup approach. If I say "backup now" it seems to work for that session, but sometimne after that the whole backup configuration seem to cancel itself. In settings the backup switch is somehow automatically turned to "off". Backups are made to an external hard drive (Seagate FreeAgent GoFlex 3Tb)
Your situation below hasn't provided enough information to give you a solution. It would be great if you could get some more details on the issue.
Getting the error number (if any), also you could go to the Security History section and gather the required information on the backup situation. You could also export the whole Security History to a .csv file and post it over here, maybe that could help us out.
Additionally, EXT HD is connected using a USB or Firewire ?
Hopefully third time lucky. The recent history file was very big, I suspect that it got stopped along the way.
Attached is a shortened version of the recent history file.
The EXT HD is linked through a USB cable.
A further point of interest is that this problem only started after my recent upgrade to Windows 7. Before that Norton 360 made backups without problems.