There may be some kind of security setting that is preventing it from working. Some networks disable Flash.
I hate to say it, but the only workaround that I've found, for this, is (if you're actually at the server or remoting in to the server) open Windows Explorer, navigate to the folder you need, then copy the full path from the bar at the top and paste it into the field for the directory you need to look in.
Can you try unchecking the "Use J2EE session variables" under Server Settings > Memory Variables in ColdFusion Administrator. This will require a ColdFusion service restart.