I'm going to be lazy today and make you solve the problem.
Did a recent security hotfix change change the way we handle UNC paths with spaces? Normally, if we open the Run dialog and type
share\ Support Library\
Support Libraryfolder opens. But recently it stopped working. Instead of opening the
Support Libraryfolder, we get the Open With dialog:
Choose the program you want to use to open this file:
Always use the selected program to open this kind of file
Can you figure out what happened recently that introduced this problem? You have all the information you need.