I had to reboot the PC for other reasons. When it restarted, the OS started a disk scan. Once this completed, the Retrospect problem went away. I found a Web page with error numbers (of course it stopped at 1126 :-)) but most of the 1100 error messages seem related to source volume errors. I'm assuming a disk hiccup. Thanks for suggestions.
Got the following during backup on XP Professional system that's been working fine for months. Backup set is on CD-R. Scanning incomplete, error -1127 (data error detected in file using cyclic redundancy check) Error number is not documented anywhere. Is a) catalog is corrupt and needs to be rebuilt, or file system/disk corrupt, i.e. chkdsk time, or c) ??? Thanks