I recently upgraded to 4.9.0 version of the VPN client, and I have only noticed this error once since then, but when I had <4.9.0, it was alot more prominent.
Cisco will come up with an error (I can't get the problem to replicate right now) but it says something about "Can't connect to Socket" or something similar, and the only way to fix it is to restart the computer or log out/in.
Well not anymore.
There is a way to fix it, you have to manually unload the kernel extension (kext) and then manually reload it. Since these commands are simple, but easily forgotten, I wrote a 3 second bash script to do this for me.
I placed it in my /Users/
Here's the script.
#written by Joel to hax0r (aka fix) Cisco's error problem with their
#kernel hook to reset the cisco function. If you have to use this alot
#try updating your Cisco VPN client.
sudo kextunload /System/Library/Extensions/CiscoVPN.kext
sudo kextload /System/Library/Extensions/CiscoVPN.kext
(told you it was easy)
put that in a file, and 'chmod +x