Lost hard drive space after Vista defrag?

Disk Defragmenter is a tool that rearranges the data on your hard disk and reunites fragmented files so your computer can run more efficiently.

Your lost disk space is probably allocated to the shadow copy System restore points, which by default takes up to 15 % of the total capacity of hard drive.

Deleting some system restore points will not give disk space back as windows permanently assigns some hard drive space for system restore, you can reduce the disk space assigned for system restore, try the below steps.

1. Click the start menu
2. Click on All Programs, and then Accessories
3. From the accessories menu, right click on Command Prompt and select "run as administrator"
4. Type vssadmin list shadowstorage into the command prompt
5. The results should tell you the amount of storage used and the maximum amount allotted
1. Type vssadmin Resize ShadowStorage /For=[your hard disk]: /On=[your hard disk]: /MaxSize=[how much space you want to allocate]
2. For example: "vssadmin Resize ShadowStorage /For=C: /On=C: /MaxSize=2GB"
3. You should get a message saying successfully resized the shadow copy storage association, and you should have more free space on your hard drive.
The disk defragmentation might have taken up hard drive space if there are errors on the drive.

You may run a scan disk command to remove the bad sectors from the hard drive and then run disk cleanup and check if it works.