Disk Cleanup, though I have all 3 versions set to not touch the thumbnail.cache. I have System Mechanic set to only run it's disk cleanup manually. It only runs the internet cleanup automatically. CCleaner is also set to leave the thumbnail cache alone.
I really thinks it's the Windows Automatic Maintenance not following how I have things set, as I have it changed to run at 11:00P.M. and I restarted my pc around 11:30 and went into Chrome and was downloading a photo and I had to wait for my thumbnails to reappear, as they looked like blank folders.
This is one of the issues I've been having only with 10 Anniversary Edition. Both times after 2 separate clean installs of it. The freezeup's/crashes I was having was found to be Samsung Magician's Rapid Mode.
I turned off Rapid Mode and uninstalled Magician. Those issues disappeared. I reinstalled Magician this morning and am leaving Rapid Mode off in it.
No freezeups or crashes and the thumbnail cache issue appeared while it was off my pc.