[nvidia-glx] using nvidia-glx-config fails because md5sum doesn't match

Binary package hint: nvidia-glx

if you install nvidia-glx or nvidia-glx-legacy and you try to do the following:
"sudo nvidia-glx-config enableonf"

it says:
"Error: your X configuration has been altered.
This script cannot proceed automatically. If you believe that this
not correct, you can update the md5sum entry executing the following
command:
md5sum /etc/X11/xorg.conf | sudo tee /var/lib/x11/xorg.conf.md5sum
otherwise edit manually /etc/X11/xorg.conf to change the Driver section
from nv to nvidia."

How it happend:
1. I installed Ubuntu 6.06 clean on a free Hard disk
2. I loaded and installed all avaible updates
3. restart
4. download and install per synaptic the package
5. this command

really nothing else!

The graphics card is a nvidia TNT2 Pro