The error "The necessary VPN sub-system is not available. You can not connect to the remote VPN" pops up when the DNE gets corrupted. In order to get it up and running the bset way would be to uninstall the client and use a VPN client from the 3.x range which does not use the Virtual Adapter.
Also if you want to use the Same 4.x client you would have to unsinstall the client manually and also clean up the registry from the os.
It uninstall procedure is different depending the type of intslled you have.
If its Install Sheild one, please follow this
Go to network properties -> Local Area Connection propertis -> Uncheck Deterministic Network Enhancer (DNE)
Then Select DNE and click on the uninstall button . Reboot the PC
Then ,
1) Remove the VPN Client (any version) from the machine using the Microsoft installer.
2) Take a backup of the registry.
3) From your desktop, go to Start > Run and type regedit.
4) Remove the following keys:
a)Go to HKEY_LOCAL_MACHINE > SOFTWARE > Cisco Systems > VPN Client.
b)Go to HKEY_LOCAL_MACHINE > SOFTWARE > Deterministic Networks and also remove the keys.
Note: Sometimes the system will not allow for the removal of this key.
c)Go to HKEY_LOCAL_MACHINE > SOFTWARE > Microsoft > Windows > CurrentVersion > Uninstall > {5624c000-b109-11d4-9db4-00e0290fcac5}.
d)Delete all the old Deterministic NDIS Extender (DNE) files:
any file starting with DNE as all are files coming along with VPN Client installations.
dne2000.sys from %SystemRoot%\system32\drivers
dne2000m.inf and dne2000m.pnf from %SystemRoot%\inf
e)The Original Equipment Manufacturers (OEM) enumeration of the dne2000.inf and dne2000.pnf files. The OEM enumeration .inf file is a file called "oem (some numeric value).inf." For example, oem2.inf and oem2.pnf.
Note: Be careful to remove only OEM files from the DNE.
dneinobj.dll from %SystemRoot%\system32. You may need to reboot before this file can be removed.
f)Delete the following file:
cvpndrv.sys from %SystemRoot%\system32\drivers
5) Reboot the machine
6) Find for the CSGina.dll file in the system32 folder rename it to CSGina.old
7) Reboot the machine
8) Disable any firewall if any is installed
Note: Remember to remove the setup.exe file from the temp files directory since it may trigger setup to run again
9) Install the 4.0.2 VPN client. – preferably the installshield version (vpnclient-win-is-4.0.2.B-k9.exe) for the web site http://www.cisco.com/cgi-bin/tablebuild.pl/vpnclient-3des?sort=release
This is the general method to uninstall and reinstall for different Windows Platforms .
Some files might not necessarily be present on you machine .
Please try following this procedure and let me know if it helps resolve the issue
