[Chris Barber] The new Parallels Desktop 3.0 for Mac is out! At first, everything looks great! Then I noticed my Cisco VPN Client v4.9 stopped working.

Thank you Chris! I’ve been plagued with this for weeks - every time I tried to VPN into work, I kept on getting the dreaded “Error 51″. Basically, there’s two solutions:

Solution One

You can manually shut down firewire internet connection interface by typing in:

sudo ifconfig fw0 down

You can also add this to /System/Library/StartupItems/CiscoVPN/CiscoVPN in the StartService() function.

Solution Two

You can uninstall VPN and Parallels, and reinstall them. Install Parallels first, then the VPN client.