Okay so I decided to delete it yesterday, since I couldn't figure out what to do with it. I even tried your method but unfortunately it didn't do anything.
Just today, at this moment of writing this, I now know why:
I happen to open up my computer again, and a few minutes during my studying, when I had a pop-up from Avast. Apparently Avast disabled access to the file because it was still observing and checking it out in the "Threat Labs", which seems to be why I couldn't open it yesterday.
So I downloaded it again (thanks for the small update to the software), and it's now working.
One funny thing, uh...
Anyway, I apologize for using your time, but thank you anyway!