System B.S.O.D. with Cisco VPN Client and CIS installed

My Windows XP system crashes up on connecting to a VPN concentrator when using Cisco’s VPN Client.
It shows a BSOD DRIVER_IRQ_NOT_LESS_OR_EQUAL caused by vsdatant.sys.

This is the ZoneAlarm Firewall driver that ships default with the client.
If you don’t need the forced ZA Firewall active or installed you can follow the following procedure to resolve the BSOD issue.

Best way would be to download CISCO VPN Client version or later and extract the package to a folder then start it with the following parameters:

msiexec.exe /i vpnclient_setup.msi DONTINSTALLFIREWALL=1

You need to extract the .exe file first with an unzip tool!

The second solution is to remove the following files from C:\Windows\System32:
  • vsdata.dll
  • vsinit.dll
  • vsdatant.sys

This will “remove” the firewall part of the Cisco Client install and thus prevent it from causing the crash.