Before I ask, here's a little about my OS and other info.:
Windows 10 Home, v. 1607; 64 bit
Dell Inspiron 5520 (he's an old man, I know...) w/ an Intel i5-3210M @ 2.50GHz; 6 GB of RAM
Bitdefender Free Edition, v. 18.104.22.1689; self-updating/scanning
There are 3 user accounts; only one (mine...
I have a bitdefender total security plan on my surface pro 3 with windows 10.
After I used the bitdefender oneclick optimizer, which said I can free up around 20gb of space using the disk cleanup, certain programs started to disappear on start menu and on the 'all apps' list.