I have a weird problem with this motherboard. I installed windows xp on this pc and the drivers from the dvd provided with the motherboard and if i leave the pc powered off for more than 5 minutes (remove power cord from psu) when i try to start it gives me a message that windows could not start "missing C:\WINDOWS\system32\config\system". If the psu is powered this won't happen. When it happens, after one or more restarts windows seems to restore itself and starts normally. I checked if the file was really missing on a preinstalled environment and it is there. Also I was able to reproduce this malfunction with several CPU's, memory modules and hard drives.

One thing I noticed is that this happens only when I use xpress install from the original cd. I installed a copy of windows and used an all driver cd to install the components and none of the software that the motherboard came with and it didn't do that anymore.

Any idea what could be causing this? Has this ever happened to anyone else? Please help.

Change your motherboard.
Your GA-MA78GM is broken.
My GA-MA78GM is same with yours.

yes i know it is broken. No good motherboard would do that. But i have trouble RMAing it since the people that I bought it from fail to see the defect and they already sent it back to me twice with "test ok". Can anyone be more specific please?

Seems to me like you already solved your problem. I doubt your motherboard is "broken", more of a software issue if you ask me. People resort to RMA too quickly, IMO.

Perhaps a difference re raid drivers - express might install different config to other install.

Perhaps bios settings being lost?? battery?? (doubt that)

It's a weird one - my best guess at the moment.

What's the other install? express or ?? full, manual, slow, boring, etc?

The mobo is new, so no bios settings lost. And yes, by installing the drivers I solve the problem tamporarily, but im not the end user of this thing. The person who will use it probably doesn't have my experience so the first time he will lose his o.s. and reinstall he will end up with windows crashing daily. And also the xpress install cd is the original software released by gigabyte. It's supposed to work correctly and it does on other mobo's like this one but not on this one in particular. I have noticed other people complaining about the same problem on forums but i wasn't able to find any reasons for it.