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Jolie: Those real long weird file names that Titanic mentions are System Restore points that are indexed between the Registry and the System Shadow copy that Windows System Restore uses. That being said, if you
DID successfully delete them, and you tried to do System Restore to undo your deletes, that's why your System Restore no longer works, since you deleted some if not all of your System Restore Points!
Unless you've got a really small hard drive (say less than 60GB) it doesn't make sense to delete those files, maybe after a year or two or if you exceed 10GB or something; which is like 100 Restore Points. Be careful not to delete any Restore Point folder within the last 90 days, since if you do delete all of them in the last 90 days you'll have nothing to Restore back to within that last 90 days, and if you keep older ones, you could lose all your work within the last 90 days (3 months).
Another thing no one has mentioned here, and it's probably trite to do so, but you should always
BACKUP all of your Personal Data on the hard drive ( for example the C:\Users\Username\My Documents or C:\Users\Username\Libraries folders) depending on which version of Windows you're running. Playing around with Registry cleaners and editing programs are
VERY HIGH RISK! That means if you make a mistake, you could crash your Windows MFT (Master File Table) and Hash Index Tables. That is often an unrecoverable problem, and requires a hard drive reformat and complete Windows re-load. If you haven't used any of these tools before, I say, "Always better Safe than Sorry", and
BACKUP ALL YOUR DATA BEFORE YOU START MESSING WITH YOUR REGISTRY!
Good Luck!
BIGBEARJEDI