Windows Server Back-up loses it's schedule after reboot

Hi,

We are using Windows Back-up for creating backups.
But every time we reboot the server, the schedule is gone.
The event logs show no errors and the backups are done according to the schedule.

We also have Back-up Exec 2010 R3 installed on the server (but we don't use it anymore)

Does someone have encountered this problem?

Kind regards,
Francois