SSD - 100GB of unknown used space

[mainemtbiker]

I am running Windows7, 64bit. I have a Crucial 240GB that has over 100GB of unknown used space. I have done disk cleanup which gained 2 GB. I have looked at hidden system files which add up to 7 GB. I could not see the swap file but I suspect that it is not near the 100 unknown GB.
After doing a disc clean the unknown used space INCREASED from 104.5GB to 109.9GB, even though the number of files, items, and sub-directories dropped. Yesterday this unknown used space was 115.7GB. I built this machine myself so there is no software on it that I don't know about. How can I determine what is using this "unknown" space and how can I minimize it?
Thanks in advance for your help.

 

[RealBeast]

A couple of suspects are the paging file, the hibernation file, and the restore points. Take a look at a good SSD optimization guide like THIS ONE for example.

 

[shadows1234]

as stated above it could possibly be restore points install a program called ccleaner https://www.piriform.com/ccleaner/download download the free one
and there should be a tab called tools and another tab inside called system restore this will allow you to delete them but keep the latest 2 just in case something ever goes wrong with the pc

 

[mainemtbiker]

Yep, it was the restore points. I had two choices in disk cleanup: Delete them all or all but the last one. I deleted them all but the last one and I went from 61GB of free space to 166GB. Which left only 3GB of "Unknown" space.
Thanks!