Pawn giving checkmate My computer checkmated me with a pawn move.

I could have taken that pawn en passant but I wasn't given a chance to do that.

Was that a fault of my computer, or is there a rule stating that a pawn giving checkmate cannot be taken en passant?
I would love to see the position; please add it to your question somehow (we can always edit it to look nice). However, there is no such rule. Either your computer doesn't implement captures en passant (improbable these days) or the capture was not valid for some other reason.