suddenly BusyBox on clients

[Bob Wooden]

Have a small LTSP Ubuntu (8.04) system at work.  Was working on Friday 
when we left.  Over the weekend, I apt-get update via ssh from home and 
this morning we are seeing BusyBox (initramfs) prompts on our clients.  
Keyboard and monitor (on server) allows , but clients see only BusyBox 
prompts.

I am searching forums now, but need to get fixed today.  Any suggestion 
regarding what is wrong?