Error while running asp.net apps in Visual Studio 2015

In my company I'm running Visual Studio 2015 Enterprise and just recently upgraded to Windows 10. Unfortunately, now I can't run any web project using versions of asp.net earlier than 5 (owin/katana) - always getting error :

"Could not load file1or assembly 'XXX' or one of its dependencies. The process cannot access the file because it is being used by another process. (Exception from HRESULT: 0x80070020) ".

Now, I've found a few posts like this and the answer is mostly that some other application is running on port 80, 8080 etc blocking visual studio's iis express. The problem is that I get this error regardless of port I'm using (even on some random 34535 etc).

The interesting part is that when I run kestrel (app on asp.net 5) it works and runs fine without any error.

Anyone has any ideas ?

Okay, so I had this issue and resolved it by uninstalling Panda antivirus, which presumably was locking the assemblies for just long enough to interfere with loading them some of the time.

If anyone else is having this issue, and there is definitely an assembly that won't load (as opposed to a port that's already been bound to) then try checking your antivirus!