We dont know that your original board was at fault yet, as we havnt tested it.
The advance replacement we sent to you has been thoroughly tested and checked (by both of us) before it was sent, and so I will not accept that the board we just sent out is faulty.
If the board is faulty now, then your PC, wiring or acceptor may be somehow damaging them.
You might also be right about the bios thing, but I wouldnt advise you to change anything there unless you know what you are doing, I think the best idea is to try the board on another PC.
Ps: the Coin Kit board is not tested to work with that coin acceptor!.
If you have a datasheet for that acceptor please post a link so we can have a look for problems there.