First, zbook and try3, thanks for your assistance. I went from about 73 GB free to 90 GB. It seems to be stable as well. The original questions I had when I posted were one, what was happening to...

1) List any of these installed software:
a) non-Microsoft antivirus: MalwareBytes 4.2.1
b) non-Microsoft firewall: none
c) non-Microsoft drive encryption: none

Results of LOGS and Tuneup

I ran the steps in post #6, here are results. Sorry for the delay
C:\Windows\system32>sfc /scannow

Beginning system scan. This process will take some time.

Beginning verification phase of...

I deleted the .dmp file. I also moved my Thunderbird profile to a different drive. Attaching Treesize and V2 output. Thanks

Sorry, had to look up folder access in Windows Defender.
.zip results attached. Thanks for your help.

299330

I did the drive properties disk cleanup along with cleaning up system files. Here is TreeSize listing:

299302

I have a Dell Inspiron 3793 running Windows 10 Home version 1909. The C drive is a 256GB SSD, and I am noticing a bunch of unaccounted for hard drive space (see pictures below). Drive properties show...