I'm trying to picture what you mean.. are you very tall or something? That's often a problem with really tall people, they can't deadlift that well.
Okay, let's see.. trying to go through the motions in my head here. Come to think of it, I lean forward a little too to get the bar in front of the knees, not a whole lot though. (I'm 6'1 or so)
OUCH .. that just hurt my quad. Oh god, no, don't tell me I'm outta deadlift commission too (and this was with no weight), okay, I'm gonna die here.. lol
rudy, try and persevere mate. If you really can't do it then you could try really heavy barbell rows and rack deadlifts (also called rack pulls) instead, with the latter you start/stop at knee level anyway. They blast your back more but are a less compound exercise than regular deadlifts - they might suit you well though.