Same issue here with Windows 7 64bit and ZA 9.1.503.00 with Cisco 5.0.07.0290.

If I run the VPN client with ZA running I get a connection to the VPN, my IP is setup and DNS servers set; but I can't connect to the internal network, all the packets are either dropped or discarded by the VPN client.

However, if I stop ZA first, start the VPN client, connnect then restart ZA everything works fine.

Also tried the connection with the shrew soft VPM client with the same result.