Intermittant no POST problem - strange symptoms

Your expertise and time appreciated!!

System - Win2000 desktop (made by ABS) with Award dual BIOS. Mobo: GA-7DX+. (AMD 761+686B)

Symptoms:- No POST beeps. Fans run. No FDD light. Master CD light always on. Monitor stand by.
Problem first started with WINDOWS freezing at start up and vertical streaks across the screen. Rebooting used to clear the problem: but not anymore.

Occasionally the PC boots but freezes on "Windows 2000 Professional" screen
At the start up, it displays,
"check system health ok, Memory 262M etc." But I can't go beyond the Windows logo screen.

Once the PC works (very occasionally with the Restoration floppy) everything works normal. But that happens less and less frequent.

CMOS battery is fine. I also tried to put XP on the machine by booting from XP CD. After the EULA acceptance it freezed.

Is this a MOTHER BOARD problem? Which parts do I need to replace???
Thanks.
Very frustrating.
Jim