X windows freezes on start

[Langdon Stevenson]

I decided to check if X works on my new server and ran into the 
following problem:

Server starts at run level 3 and operates fine.

When I:

   startx

from the command line, X loads, then when it reaches the point where it 
displays the splash screen for login, the splash screen flashes up for a 
moment, with the cursor displaying as a hash of colour, then the screen 
goes blank.


I can ssh into the machine from another workstation, so the machine 
hasn't hung.  "top" reveals that the X process is now thrashing the CPU 
away at 100%.  But no response from keyboard or monitor of the server 
itself.

Only way to bring it back is to do a shutdown via the ssh session.

Can anyone suggest how I should go about debugging this issue?

Regards,
Langdon