Change Computer on PBeM, help!

[Imp]

So if I just give up the game then I will certified as "Decisive Loser"

Maybe not if they are decent & its circumstances beyond control if explain will probably do one of 2 things.
1) Nullify the game if you will give a rematch.
2) Agree with you what is a reasonable victory condition if the game has got far enough.
They tend to be good people over there tell him straight up now rather than hoping to get further & will probably be fine if a bit miffed. The rule is there for people that vanish or muck about not rare circumstances.