switch kernel, Xorg conf

[Mihamina Rakotomandimby]

Hi,
I have a generic kernel and a -xen kernel on my box.
I use the Xorg nv driver
When I configure Xorg on the generic kernel, it works, with the right 
screen resolution.
Then if I switch to the Xen kernel, X configuration is broken, I have to 
"dpkg-reconfigure" it.
Then it works, with the right resolution.
Then if I get back to the generic kernel, it breaks again.... and so on.

Is it a feature?