In my case the solution was related to NotePad++ being the default application for opening .vbs files. If you have the same situation, here’s an elaborate solution:
http://igordcard.blogspot.co.il/2012/03/unable-to-write-inside-temp-environment.html
In a nutshell, in the registry, you need to go to HKEY_CLASSES_ROOT\.vbs, and set the (Default) entry back to the string VBSFile.