I too have Windows 2012 Essentials eating up hard disk.
Yes, I tried chkdsk.
Yes I have tried optimization.

I too, installed WinDir ....    Unfortunately, in this case...  it has found 70-GB of something it can't identify either.  On a C:\  partition of 80GB, it was horrific.

Just a large "blob" ... is can't identify.. and has no extensions assigned to it either.   I am at loss as to where to go.
This is a small server.. and is not really connected to anything but the Internet (yes firewalls are up.)

I finally had to use a third party tool to increase the space. Now at 100GB, and whatever it is, is still consuming about  880MB per day.

Any help or suggestions would be greatly appreciated.

• Edited by Merle Wait Wednesday, July 22, 2015 5:32 PM

So I downloaded, TREESIZE from Jamsoftware....

Ran it as ADMIN(which is what I what I did with  Windirstat.

Using TreeSize, it identified them as HTTPERR logs... 
Use KB article:  https://support.microsoft.com/en-us/kb/820729

Deleted the log files...    Unfortunately for the box itself.. its all been taken off line and disabled for the moment; but at least I know.

Thanks for everyone's help

• Marked as answer by Merle Wait 15 hours 45 minutes ago