Okey, so I think i found the problem. I used the Process Monitor program that you linked to check what was going on.
It couldn't find the path because of whitespaces in the name of my Windows User Account.
For some reason it converted the path from this:
"C:\Users\User Account Name\AppData\Local\Microsoft\VisualStudio\12.0\Extensions"
to:
"C:\Users\User%20Account%20Name\AppData\Local\Microsoft\VisualStudio\12.0\Extensions"
Paths without the "%20" whitespace conversion was Okey.
I've created a new Windows User Account without any whitespaces and it worked fine!
Do you think it is something that you can fix?