Hey, I'd just thought I'd mention another problem that alot of people around the interwebs are facing, and how to fix it. No-one ever resolved it, and it's annoyingly simple, at least in my case.
PROBLEM:
This appears everytime you try to run it in any kind of way:
Free the WADs *testing version* by Superken7
cannot open file freethewads
A few people mention they have been able to run it fine on other wads, same as me. The ones not working were set to Read-Only. To change, right click>properties on the wad file. And then uncheck the hopefully checked "Read-Only" box at the bottom of box in the general tab.
i cba to make an account in another forum, so hopefully sufferers will google the problem.