We see this when folk run any of those registry cleaners. The entry that told Windows to not report low space on those drives is removed.
You have a choice. Turn off the warning or ignore it. And if you are like most, you run the registry cleaner and the warning comes back.
AGAIN, this is a repeated error and post I see a lot.
I have an HP Presario CQ57 laptop with windows 7 Premium. I keep getting the message that my backup disc is full,,like the others:
Data file backups for this computer on HP_TOOLS (E:) and the D: are both full, when I try to delete either one I get told "you will not be able to restore files from this computer from backup" how can I solve this problem,,I did do a DELETE and run backup now but it lasts less than a week. I use my laptop for info and games,,not business.