Hi Edith.
The settings section I mentioned refers to one particular area of Registry Mechanics scanning, and that is the "temp files and shortcuts" section. You can choose what to scan for in that particular area.
This is the online Registry Mechanic manual, and this shows all the areas which RM scans, which are all related to your C: Drive, your operating system.
http://www.pctools.com/registry-mechanic/help/8.0/
If it's any consolation, System Restore has failed for me on quite a few occassions, and it is definitely a debatable point as to whether RM's scan and removal of items from "System Volume Information" has anything to do with it.
I'm not an expert on System Restore, and I have it switched off for my other drive, my E: Partition, as there isn't anything I remove from there that I would want replacing.
However, RM picks up a lot of items from that drive, and I've always deleted them, but who knows whether removing these will affect how my System Restore works.
Another member, Augeas, posted recently about the possible consequences of deleting old Restore points. Basically raising the point that newer Restore Points may need information from older ones to work successfully.
http://forum.piriform.com/index.php?showtopic=22229&hl=
This doesn't give you a definitive answer as to why System Restore has failed, but maybe give you something to think about.
I would definitely leave that item unchecked for now, as I intend doing, and see how it goes.
I would also suggest, in case you have a corrupt System Restore point, making a new one, and clearing out all the old ones with Disk Cleanup, and start with a clean slate. This is a good thing to do occassionally anyway.
You can do it by this method.
Remove Restore Points:
To remove all restore points except the most recent restore point, follow these steps: Click Start, and then click My Computer.
Right-click the disk in which you want to free up space, and then click Properties.
Click the General tab, and then click Disk Cleanup.
Click the More Options tab, and then under System Restore, click Clean up.
Click Yes to remove all but the most recent restore point.
Click OK, click Yes to proceed with this action, and then click OK.
LINK:
Hope this helps.