Here's one for the Corel employees. What can cause an ARM on an otherwise completely stable system? And why do they seem to be completely random? Happens to me when I try to save files.
Small amount of free disk space, plus highly fragmented files, are the most probable cause.
Start by emptying your trashcan, then deleting all the file in your system %temp% directory, and then empty the trashcan, again. This should give you more working disk space.
I have 4GB of RAM, and 105 GB of free space on my hard drive.
I think it's most likely the saving at the same time as the backup is made.