It's just the darn machines themselves. Last year I did a smart thing and sprang for six sessions with a personal trainer. And he was incredibly helpful in getting me to be comfortable with and around the equipment. Even if I did have to move the bar to the lightest weight setting, at least I could sit down on the equipment and have some clue as to what I should be doing.
So now that I'm back at it, gym-wise (kinda/sorta), those weights are calling my name again. And I've decided that the best way to deal with them is just to suck it up, walk over there, and get my lift on. Oh, and have this picture in my head: