gigabyte GA-6VXC7-4X booting problem

some one suggested that it might be a problem with the mainboard.

its no longer reboot like it should be.

I run an OS/2 machine.

after I do a shutdown procedure & C-A-D to reboot. screen goes black.
the reboot screen never shows up.

sometimes it reboots normally, but most of the time it doesn't.

I'm also not able to turn off the computer using the on/off power button
and the reset button. the drive & other hardware lights stay on.

I've checked the bios and didn't see anything that would cause the behavior.

could the video card be going bad?

suggestions anyone?