Fraser Digby was at fault for the first two, scored by the Brazilian striker Marcelo, and although Palace looked the better side for the first 20 minutes of the second period, Bobby Ford's tap-in from a rebound off the post ended any hope of an unlikely comeback.
The Palace manager Steve Coppell directed his disappointment not at his players but at the would-be owners who are dithering over buying his club.
"They should put up or shut up. This is getting ridiculous. They have to start contributing financially as of now. They should start taking decisions now or a third of the season will be over before the takeover is complete and we will be left picking up the pieces."
His players found themselves picking up pieces from the whistle as United dominated the first half, although 20 minutes had gone before Sean Murphy found Paul Devlin down the right. Digby got a hand to his low cross but could only parry it to Marcelo for a simple tap-in.
Martin Smith sent a snapshot wide and drove another into Digby's midriff before Marcelo scored his second on the stroke of half-time. The substitute Wayne Quinn was the provider this time, and Digby was again at fault, mistiming his punch to allow Marcelo to head into an empty net from close range.
To their credit, Palace responded by taking the game to United whose goalkeeper Aidan Davison, standing in for the suspended Simon Tracey, failed to cling on to a sliced clearance by his own defender Jody Craddock and was relieved to concede a corner, which he flapped at before his defenders scrambled the ball away.
Davison's previous appearance had been in the Blades' 6-1 defeat at Manchester City but he recovered his confidence to get his body behind a deflected Steve Thomson shot.
But the Eagles could not sustain their revival and Devlin came close to increasing United's lead with an angled shot that shaved a post which Martin Smith hit shortly afterwards with an almost identical drive. This time Ford was running in to tap in the rebound.
Marcelo narrowly missed a hat-trick when his shot across the face of goal flashed past the post and Morrison's goal for Palace from Simon Rodger's corner in the final minute offered Coppell little consolation. But the ease of United's victory did not satisfy their manager Adrian Heath who described it as their worst performance of the season.
"The result was good but the performance wasn't. Had we been playing a team with greater confidence than Palace we would have been well beaten," he said. "Fortunately our two centre-halves were on top of their game but that level of performance is not acceptable."