Thanks for your quick response.
There is something weird going on with my system - but other than opening/closing MC, MC works fine. I'm sure it is not an MC bug (obviously not, since it works fine for everyone else), but hopefully the computer experts here can point me in the right direction.
1) The only security software is Windows Defender (the built-in/free MS program).
2) I'm on Win8.1 x64 UPDATE: now on Win10 with MC21
3) I am the only user. I have an admin password but I have Windows setup to not ask for it when I boot up.
4) The computer is only used for HTPC things (but there's a lot of other software on it) such as:"
MedioInfo, AnyDVD HD, ClownBD, CloneBD, Clone DVD, MakeMKV, Hauppauge Colossus capture program, my 3Ware RAID card hardware/software, nVidia driver, and maybe a few programs others related to hardware installed (USB3, TV Tuners, etc.).
4) I don't run any plugins.
If I can't fix this with a full-clean install, maybe a fresh upgrade to Win10 (in another month or two) will do the trick.