[K12OSN] Fatal server error: No screens found

[Hung Phan]

Hello, folks

One of our K12LTSP client quit working and we put in a new one with  
higher spec: 1.4 GHz, 256MB and Intel NIC card.
We then receive this message:
Module Loader present
[EE]No Devices detected

Fatal server error:
	No screens found

Xserver failed, press enter to continue

We think this maybe something related to video but not sure. Anyone  
run into this problem? and your solution?

Thank you very much,