It's possible that an updater ran for C4D Lite and it got the latest 16.038 while using AE 13.6.1, and maybe that’s the problem...it's an idea anyway.
Check for this folder and delete it:
C:\Program Files\Adobe\Adobe After Effects CC 2015\Support Files\Plug-ins\MAXON CINEWARE AE
Re-install AE 13.7
Thanks, I figured it would come down to reinstalling. I did as you suggested and everything seems to be working again. I was afraid I would lose all my settings and stuff but it appears everything was retained.
Glad it worked!
Thank you, this worked for me too.