Backup Exec 2010 R3 - Recurring Backup failing

Afternoon all,

This is my first post and was wondering if anyone could shed some light on a recurring backup failure I keep getting.

The Server is Server 2003 (SBS) SP2 and I am running Backup Exec 2010 R3 on it.

I run a daily "Full" backup which Overwrites the media and runs fine most days. However, every 3 weeks the job will fail with the error message (see attachment).

It appears to be related to the GRT aspect of the exchange backup but am unsure as to why it fails every 3rd week but is fine other than that?

Any help would be appreciated.

Regards

Dan