ABR11W scheduled tasks suddenly fails with no error description

Hello Forum Users

I am running the ABR11W product with the latest build 17318 on one of my customer sites.

I've been having success with a monthly full backup on the 1st Sunday of every month and daily differential backups for the rest of the week.

Today I suddenly received the error below for the differential backup with no clues to the cause of the error.

1 Information 2011/10/13 18:00:06 Command 'Backing up' is running.
2 Information 2011/10/13 18:00:26 Analyzing partition '1-0'...
3 Information 2011/10/13 18:00:29 Create Differential Backup
From: Disk '1'
To file: "file://10.10.10.96\public\acronis\marthie\backoffice2_2011_10_11_14_20_18_671D3.TIB"
Compression: Maximum
Exclude: Files matching mask
Match criterion: *\System Volume Information\*{3808876B-C176-4e48-B7AE-04046E6CC752}; ...

4 Information 2011/10/13 18:00:30 Pending operation 151 started: 'Creating partition image'.
5 Information 2011/10/13 18:00:30 Locking partition 0-0...
6 Information 2011/10/13 18:05:57 Pending operation 151 started: 'Creating partition image'.
7 Information 2011/10/13 18:05:58 Pending operation 148 started: 'Saving partition structure'.
8 Information 2011/10/13 18:06:01 Command 'Backing up' has completed successfully.
Task 'Differential backup' has failed on machine 'BACKOFFICE2'.

Your assistance is appreciated.

Regards,
AJ