Bottom side Mansfield collected their first win in nine games after two goals in four minutes from Michael Boulding.
Ian McParland was taking charge of County for the first time but his team did not break through as the Stags kept their first clean sheet for 20 matches.
The deadlock was broken after 57 minutes as Matthew Hamshaw was fouled trying to turn Austin McCann and Boulding rammed in the spot-kick.
He then finished superbly after a neat flick from Simon Brown.