My hard drive is complaining it is low on disk space, but a strange thing seems to be happening: Explorer reports 10Gb of available space (on a 120 Gb hard disk), chkdsk in the command prompt does the same but if I use a disk space tool such as SpaceSniffer or WinDirStat, only 50Gb of data is found. My guess is that there somehow is a hold on a large block of disk space (but that's just a guess) because of a prior very large (40 Gb) download attempt that didn't complete. There isn't 40Gb of files on the drive (hidden or visible), yet Explorer insists that something is there. How can I claim back this hard disk drive (without formatting my hard disk)? SpaceMonger is providing a clue, reporting four unscannable folders which add up to 43Gb: C:\RRBackups C:\System Volume Information C:\Windows\Csc\v2.06 C:\Windows\System32\LogFiles\Wmi\RtBackup Does anybody know what these folders are for, and how I can claim back at least some space? Restore point claims about 4Gb, so that doesn't seem to be the main problem.