I have installed a VPN client with no apparent problems. When I tried to open it I got the following message:

What driver? What module?

Where am I going wrong?

there is normally a service on boot which loads the service module, and this module needs to be loaded in advance. personally i would recommend NOT using the cisco official client, and instead try out vpnc, which doesn't need kernel moduels and is generally a lot simpler and nicer.

Check /opt/cisco-vpnclient/bin/cvpnd and see if the installer managed to set this setuid root:

ls -la /opt/cisco-vpnclient/bin/cvpnd

---s--x--x 1 root bin 2178328 2006-06-21 17:14 cvpnd

For some reason or other it failed to do this on my Ubuntu 6.06 box, so I had to set it manually:

chmod 4111 /opt/cisco-vpnclient/bin/cvpnd

This fixed the problem for me, after restarting vpnclient_init i was able to connect as a normal user.

I am on SUSE-10 and ran into the same error
[Running on: Linux 2.6.11.8-FC4_lc1 #1 Wed Sep 28 23:09:46 PDT 2005 i686
Config file directory: /etc/opt/cisco-vpnclient

Could not attach to driver. Is kernel module loaded?
The application was unable to communicate with the VPN sub-system.]

Changing setuid didnt help. At somepoint in time the suse update process seems to have created a new module 2.6.13-15.10-smp in /lib/modules, which didnt had CiscoVPN/cisco_ipsec.ko. I also had 2.6.13-15.8-smp, so just copied the CiscoVPN to the new smp and restarted my vnclient_init. (/etc/init.d/vpnclient_init restart). This fixed the problem for me.