United were well aware of the dangers of former teammate Paul Harsley, but eight minutes in Peter Beagrie upended him to give away a central free-kick 20 yards from goal.
Martin Smith stepped up to curl the ball into the top right corner of the net, and give the under-fire Cobblers the lead.
Beags' cross to Torps five minutes later should have lead to an equaliser, but Torpey's poor header was easily saved by Lee Harper. The first of several chances spurned by the club's record signing.
Northampton were also missing their shooting boots, with Marc Richards rounding Andy Butler before firing wide and Chris Carruthers' header coming crashing back off the crossbar.
Richards went close again on the half hour mark, forcing Sam Russell into a good save with his legs before Mark Jackson cleared the ball to safety.
Matty Sparrow had been struggling with a calf injury before the match, and he limped off to be replaced by Wayne Graves.
It didn't take Graves long to settle into the game - going down in the area as he tried to get on the end of a cross from Steve MacLean but failed to convince the referee.
United were hit further by injury in the Second Half, with Lee Featherstone stretchered off to be replaced by the below-par Kevin Sharp.
A deflected shot from Richard Kell in the 57th minute levelled the scores and boosted United's confidence - with Torpey again guilty of wasting a golden opportunity to score five minutes later with a weak effort which was saved by Harper.
Paul Trollope almost turned Peter Beagrie's corner into his own net, with Chris Doig also seeing his headed clearance going narrowly wide of his own post.
The game petered out into a stalemate which was a fiar result, but does not do either side any favours in terms of the Third Division table.