Ubuntu Desktop locks

[Ryan Rix]

Alexander Henry wrote:
> This has been happening about once a day or every other day.  The 
> desktop simply locks up.  I discover that the cursor doesn't move, then 
> I try alt-tab, ctrl-alt-backspace, ctrl-alt-delete, clrl-alt-F*, 
> nothing.  Have to power cycle to break it.
> 
> Any ideas?  It's a rather hard problem to search for.
> 
> This happened since I upgraded to 9.04
> 

Can you ping/ssh into the box?
If you can ssh in we could get a lot more info on your problem.