Apple

VPN Client for Mac

With my current client I've been granted access to their internal network via VPN with the caveat that I have to use a specific VPN supplier, namely Checkpoint. Luckily they do have a VPN client for OS X called "VPN-1 SecureClient R56". It works pretty well actually but I have had a problem when not using it that the airport task runs at 100% processor until I kill both SecureClient and airport. Not ideal. The Apple help on the subject is worse than useless:
Make sure your third-party VPN client software is up-to-date. Contact your network administrator or the manufacturer of your VPN client software.

What I have found after some playing around is if either the VPN or airport are in use then the problem doesn't occur, if neither are being used is the time when the processor ramps up. So if you remember to turn off the airport connection before you shutdown, then when you restart you don't get the processor hogging issue. I used to just leave it on all the time so this is an annoyance but it saves having to go through the whole killing tasks process after startup each morning.