What's the path you're trying to enter?
I'm curious as to if yo're being affected by the same issue as described in the below article, which states that specific strings cannot be used.
http://www.symantec.com/docs/TECH199851
As an example, I've tried to add a security folder exception for "c:\JavaScript\temp" and I get the attached error (on a test 12.1RU5 box)