[hosiminh]

If partitions are formated into NTFS , MTF might be eating to much space
Otherwise you might be using System restore (folder "System Volume Information" on root )
Run chkdsk disk with /R /F X: swithes where X: are your local drives:
start/run / cmd

chkdsk /R /F C:
and
chkdsk /R /F D:

I guess drives will be checked when next reboot occur.

If you use win xp , installing SP1 might be a good idea.

start/run / compmgmt.msc
and check storage/Disk managemet if there are any unallocated partitions left