Parallels Desktop 9 and OpenVPN issues

I am running OSX, with Linux Mint and OSX on top under Parallels Desktop 9. The two virtual systems are using a "Host Only" network. The underlying OSX (10.8.5) is connecting back to a OpenVPN server using Tunnelblick (an OpenVPN front-end). When the two virtual systems are up the routing to the VPN seems to get confused and no traffic flows down the VPN. When both VMs are down, the VPN runs fine. Any suggestions or thoughts on troubleshooting?