A workaround is to change the traffic to unicast. Set up a WINS server the Windows naming scheme works similar to DNS. Set up the WINS server in your LAN environment and enter its IP address in the VPN network parameters tab. This tab is on the properties of the VPN users group in question. The VPN User group should be the default IKE users group. Depending on what operating system your clients use, you may need to enable NetBIOS over TCP on their network settings. In Windows XP NetBIOS over TCP is a semi-default setting. If the client doesn't get a setting from a DHCP server, it defaults to enable the traffic.
For additional information go to the document:
Troubleshooting Microsoft Network Neighborhood After Establishing a VPN Tunnel With the CISCO VPN Client
The following is an explanation on the difference between broadcast and unicast.
You have a message to get to your coworker Bob. When you're in the office, you just yell out "Hey Bob!" this is broadcast.
Now you're out of the office. Yelling for Bob is not going to work. What you do is unicast, by calling the floor supervisor and say that you have a message for Bob. The floor supervisor then yells "Hey Bob!"