When i click on the properties of my C: partition in My Computer (Windows XP) it shows that i have 4.27 GB used, but when i select all the files and folders on the c: partition windows shows their size to be 2.99 GB. What happened to the (4.27 - 2.99) = 1.28 GB.

Note: I have selected for the hideen files and the protected operating system files to be visible.

Thanks!