Ghost 15 Snaphot 3 can't read sectors

I just discovered that my backups have not been completing for a while.  The initial error repor was something to the effect of "this drive is giving signals that it will fail"  I ran chkdsk overnight on the drive that the backups are written to, and this morning the mahine was on, but the monitor would not display.  I rebooted, and one again tried a backup with Ghost.  It now gives the "snapshot3 can not read 819 2 sectors" error.  Does this mean the problem is on the drive I am backing up, or the one I'm trying to write to?  Any action results in a backup failure.

 

Does anyone have ideas about what this means, and what to do about it?

 

Thanks.