I assume you’re using Windows. Windows networks use port 137 to communicate with virtual drives. CA as most firewalls detects networks and gives you the option of allowing network traffic by automatically allowing traffic from the IP address of the approved network.. Unfortunately, it may not detect virtual drives, in that case you must manually open the TCP port 137. Go to Firewall, Main, Custom, and open TCP 137.

Firewalls are very dangerous. They all work differently, and many exceptions, like virtual drives, may not be detected. So you may be blinded, and without a considerable knowledge of ports and how they’re used, you may be in big trouble. Often when a firewall closes a port, uninstalling the program will not open the port. Even restoring Windows XP to a previous state may not open the port.

I know of one person who in frustration reformatted his hard disk to get rid of the effects of Zone Alarm.