So, my 535i clutch stopped working in the middle of no where (half way between Kit Carson and Eads, CO), I had passed a semi and went to put the transmission in 5th, and it wouldn't go, I noticed that the pedal wouldn't return from the floor, so I pull over.

I pulled the pedal up and then I have pressure about 1/4 of the way down, and it won't go any further (at least that I was willing to try, didn't want to break anything worse than it was.) I play with it for about 20 minutes and call for help.

As I'm waiting I notice that when I push in the clutch I can feel something, like the throw-out bearing isn't there and the lever is rubbing on the pressure plate, although there was no noise when the clutch sopped working, so I'm pretty sure it isn't the throw-out bearing. I was pretty sure it was something wrong with the slave cylinder.

I get it home, and pull the slave cylinder, everything looks fine. I re-install the slave cylinder, and now I have no pedal, it goes all the way to the floor. I try pumping it, and then bleeding it, still nothing...

I'm stumped, anyone else have any other similar problems? or have any ideas?

I should probably mention that I swapped the engine about 400 miles ago, I checked the bearing at that time and it looked fine. The car has 227k miles on it and was neglected before I got it (it sat for about 8 months with about 3 inches of water in two of the cylinders.)