The problem symptom is that 1) CD is completely ignored and OS boots from a HDD, 2) booting process begins but it stalls. There is one kind of bootable CD which still boots which is DOS CD. I switched the optical drive to a new one, but the problem symptom is the same.
Could it be that something happened with the motherboard? Any suggestion is appreciated.
Edit: I found the cause of the problem: I recently added one 1GB RAM stick on top of two 1GB sticks. The one added was removed then the problem gone. I do not know why, because everything else looked normal.
Edited by churin, 01 March 2009 - 12:02 PM.