backup failed with code 100121

I’m running comodo backup v. 3.0.171317.130 on a windows 7 64-bit operating system, backing up to an internal drive. The drive to be backed up contains 175 GB of data. The target drive has 600 GB of free space. In two weeks of trying, I have yet to successfully complete a backup. The thing stops, generating a fail code that I’ve not seen referenced elsewhere. Here’s the output from my latest attempt. Does anyone know what a 100121 code means?

22:34:41 Creating new backup…
22:34:41 Creating full backup “D:\ComodoBackups\Partition_CO_full_part.cbu”
22:34:41 Initiating Backup Operation…
22:34:41 Gathering Information…
22:34:42 Performing Backup Operation…
23:04:14 Error reading from disk.
23:04:15 Backup process failed with code 100121


The error indicates a timeout period expired.
Does the error always occurs at the same percentage of completion?


Yes, it occurs at the 25% completion point (according to the completion bar). Screen saver is off. I just noticed that the power settings have the computer going to sleep after 30 minutes. I’ve changed that to never – let’s see if that does anything.

Well, I shut off the power saving feature that put the computer to sleep, but I still get the 100121 error. The backup still stops at 24% completion.

I am getting the same error when trying to do a full or increm backup of C Drive. I get zero percent completion. If I used the Wizard, backup works fine.