Houdini, Rybka... all of them chess engines that run on your PC. A quick look will show you what I'm talking about.
Secondly, you can't refute their allegation. Just take it with grace, and move on to the next game.
being accused of using "a Program"


Get used to it. There are plenty of sore losers that make such claims. Especially if you defeat a higher rated player, and you play slowly.

Um, you're innocent until proven guilty. It's his responsibility to prove that you were cheating. If you didn't cheat, tell him to go pound sand.

I was just accused of using a program because the person I played kept playing into the Max Lange without really knowing any of the moves past move 16 or 17. So we would both play out the book moves, get into that position where black's rook is on d3 (I was black in all of these games) and then he would make some non-book move that would immediately lose. The sore loser posted on my wall that I must use a program.
I have been accused of cheating by using "a program". firstly how can you use a "program" and secondly how can you refute this allegation by a poor loser?