66 ( +1 | -1 ) ...3. c5 was risky because it overextends your pawn (thus your c and d pawns got rocked within 10 moves). Continuation for Semi-Slav Defense normally goes 3. Nf3, but you know... to each his own.
I think I would've chased away the bishop with 14. Na4 before doing 14. f4. The trading after 14. f4 didn't serve much of a purpose, and it seemed that the computer kept winning a pawn in trades.
You moved 21. exd5 at the perfect time. That saved you drastically by destroying black's pawn structure.
I got lost around move 40 and didn't want to restart. I'm curious, though, as to which rated "player" you played this game on Chessmaster.