capcom zn-2 locking up

[Nostromo218]

I got a capcom zn-2 Rival Schools board recently and it works fine, unless I do one of two things. If I let the attract play all the way though it freezes on a white screen, or if I try and run a memory test it freezes.

Can anyone lend any advice on where where I should start poking around to get it back up to 100%?

Thanks