As you have updated your kernel,i would think that you will need to reinstall your graphics driver.
Looking at your previous post you are using an Nvidia graphics card.
Edit your xorg.conf file to use the nv
driver,then restart X.
That should hopefully give you a working gui,so you can then sort reinstalling Nvidia drivers.
Do I have to update the drivers every time the kernel is updated?
If you go from a 2.6.24 to a 2.6.26 kernel,then yes you will need to compile the Nvidia module.
If you go from 2.6.26-1 to 2.6.26-2 as a security patch/update you should be okay.
Bare in mind these are just examples i have used.