Windirstat shows 166 GB in 244 GB Drive C as unknown

Dear All,


My desktop specs,


ACER, Intel I3 3.70 GHz, 4 GB Ram, 14 TB with 4 partitions of 244 each. In drive C, Windows 7 professional service pack is installed.


Recently i started noticing huge loss of drive space and i am left of only with 39.10 GB of space. My Windirstat shows 166 GB as unknown.



I have not installed any games and my antivirus is K7 Total security.



But i noticed a strange thing, when ever i ran disk cleanup in drive C, my hard disk free space gets reduced and when i tried with clean up system file and under the tab more options clean system restore and shadow copies, also did reduce the free space again.


Please help me with the solution. i have attached the screen shot of Windirstat.


Thanks and Regards,




V.Mahesh Kumar.

Hello vmk1509

Here is how to use Disk Cleanup - Open and Use

You can also use Disk Disk Cleanup to read how much space is used up by the file type, and determine how much space will be freed.

Unknown file types are usually system files, for example, System Protection.

Have you run a Check Disk recently?

Hello iko22,


Thanks for the reply.


After Disk cleanup the free space get's reduced.



Chkdsk has been run twice once while bootup and another from windows by right clicking drive c and properties, tools, check now.


The free space has not been recovered and still 166 gb in not yet released.


Thanks and Regards,




V.Mahesh Kumar.