Dear users,
  I will apologize in advance if my question will sound to "elementary" 
for you but an your advice will be very welcome.

 I have a Ws with Scientific Linux 5.5 with a Nvidia quadro 2000 grafic 
card (I have installed the drivers by Nvidia-86_64-230.10).
 Well at the Ws reboot I got some strange errors for the initialization of
 runlevel 5 and in particularly was failed the load of nvidia modules and
 for kbd I got the messages that no driver are available.

  After some investigations ;-) I found that other people have installed 
on the Ws a program FreeMat which maybe has changed the previous 
configurations. In fact my kernel was 2.6.18-274.12.1.el5 and now I found 
that it is become 2.6.18-308.8.2.el5.

I guess that the problem of the xserver initialization (the Ws now start 
at runlevel 3) will be due to some problem in the grafic drivers due to 
the program installation. Since, for now, I do not completely recovered 
what was done during this installation my doubt is:

Try to reinstall the previous nvidia (or more recent) drivers on this 
kernel or by grub restore the previous kernel (2.6.18-274.12.1.el5) and in 
the latter case how delete the new bad one?

Thanks in advance for yours hint
Massimo