Unknown storage on c: drive

[Jerzy]

There is only 2GB of free space on my 105GB c: drive. However all the files
consume only 40GB. Using a WinDirStat utility I found that there's an
<Unknown> area of 64GB.
I switched off making shadow copies and there are no restore points available.
I've checked using "vssadmin list shadowstore" that this is not shadow
storage, as there's a 300MB maximum limit. I've also run "chkdsk /f c:" but
that didn't reclaim any free storage.
I've searched on the Internet, but given solutions do not solve my problem.
On my system there's running Symantec Norton 360 making backup copies, but
that was already included in those 40GB of storage used.
My operating system is Windows Vista Business, Polish Edition.
Please help bring me back my 64GB.

 

[Nonny]

There is only 2GB of free space on my 105GB c: drive. However all the files
consume only 40GB. Using a WinDirStat utility I found that there's an
<Unknown> area of 64GB.

What does Disk Management tell you about the drive?

 

[Jerzy]

In the meanwhile I've removed the backup made by Norton360, which gave me 7GB.
I've also found out that some Lenovo Restore program makes hidden backups on
the drive. Hopefully, I could exclude some large files from backing up, which
made another 10GB free. Still, there are 5 such Lenovo backups, two of which
use ~6GB, and another three using only ~1GB.
Windows now reports that there are 18,5GB free, and WinDirStat shows that
all files consume 32,8GB and there's an <Unknown> area of 54GB. Probably 15
out of those 54GB are those Lenovo backups, but I can't figure out what's on
the other 39GB. Is there a way to find out?

Disk management says that the C: drive's capacity is 105,35GB and there are
18,55GB free. The disk is (translating from Polish): Healthy (System, Boot,
Swap file, Active, Backup, Primary partition). Filesystem is NTFS.

 

[andy]

Run a disk usage program such as ShowMan.
<http://www.satsignal.eu/software/disk.html#ShowMan>