Resolved C-Drive shows 750GB used but only about 75GB in folders?

I was shocked to see that the properties for my new 1T C-drive was showing 750GB in use and only about 180GB free (using Win7x64 Pro).

I scanned all the c folders (with an old TreeSize utility) and get about 75GB which I confirmed with a quick manual scan using Properties.

I also deleted the Recycle Bin before doing all this and I disconnected the comp from my home network. Other than the D: drive, there are no other drives listed.

My usual full C-drive backup using Acronis is also about 75GB.

1. How can I fix this?

2. Would a Disk Cleanup or Defrag help?

3. Please also recommend a newer Win7 utility that will show all the folder sizes from highest on down since doing a Details display of the c drive folders just shows a blank column under Size.

 

Google up FolderSize to identify where the bloat is. You might check the size of the pagefile.

 

Thanks (sorry for the delayed response).

I found some old hidden backups that were not getting cleaned up correctly.