Wrong Drive usage?

Hi im running windows vista RTM and i have about 300GB of space on the drive, i only have vista installed, and its telling me that i am using 40GB of my drive. When i select all my files in the drive it only says 7GB of space used. Is there any way to fix this? Or am I going to have to format? Thanks alot!!

I've never run Vista, but I know it still uses the System Restore feature ala XP (albeit somewhat improved from what I've read about it). Depending on how long you've been running the RTM / how many Restore points have been created, and how much HDD space you have allocated to the SR directory... up to 12% of the free space on the drive (36 GB on a 300 GB HDD) can be used. You may want to delete all but the most recent Restore point... Disk Cleanup tool | "More Options" tab | System Restore --> "Clean up" button (assuming Vista uses the same Disk Cleanup tool as XP, and has the same features), and then reduce the amount of space that SR allocates to maybe 2-5% or so. If you don't ever plan on using the SR feature, then you might as well disable it altogether.