I do insure that all instances of makemkv are uninstalled. There are no hidden folders. I've removed my antivirus, I reboot between un-installs, I empty recycle bin, reboot after install, etc. I make sure nothing is showing in Task Manager. I still get an error and this has been going on for months.

Any other blinding flashes of obvious that should be tried on my Windows machine before I completely give up on this?