Scripts will not load Visual Studio 2015 as of 5.3.1f1

Just upgraded to 5.3.1f1. Tried launching Visual Studio, but it only gets to 1/3 of the loading bar, gets stuck forever and launches MonoDevelop instead. I tried repairing Visual Studio, tried reinstalling Unity. Gave Visual Studio and Unity "Run as Admin". Doesn't work.

Any ideas?

EDIT: I've tried to change the default script editor to Mono, then back to VS2015. It still just loads 1/3 of the way then hangs indefinitely and opens Mono. I've done a full system cleanup with advanced systemcare after uninstalling the prior version and rebooted my machine. I'm reinstalling it now and I will report the results.

EDIT 2: The above didn't work. Starting to get actually frustrated with this. Completely re-installed twice, cleaned my system and any leftover files afterwards, and it still loads up Monodevelop.