I have four partitions, two of Windows and two of Linux. The Windows partitions have sizes 129 GB - C drive and 4 GB - W drive. When I check the amount of used space on C drive directly by right clicking on the C drive icon and then clicking properties, I get 55.1 GB used space and 74.1 GB free space. However when I select all the folders in C drive and then calculate their size, it comes out to be only 43.4 GB - a difference of nearly 12GB. The paging file size is only 1.5-3GB so that cannot account for this. Otherwise the computer is working absolutely fine and giving no problem at all. My computer is Dell GX620, Intel Processor 640 3.2GHz, 1 GB ram, 160GB SATA Seagate harddrive, Windows XP Professional SP2 and Suse Linux 10. What could be the cause of such a huge difference between the total size of folders and the used space on the disk reported by the computer?