I find that both Parallels and the CiscoVPN client get confused with all the changing I do on my network (using wired, wireless, Verizon card, etc). Sometimes it’s tough to get it all sorted out again. I’ve gotten it pretty consistent now. I just restart the appropriate kernel extensions and it all works out.
Before I run Parallels, I run this command in a terminal:
sudo SystemStarter restart Parallels
Likewise, I can kick Cisco’s VPN extensions with a similar command:
sudo SystemStarter restart CiscoVPN