@makari: I'm having the exact same issues, although I haven't lost saves but I'm stuck at the map only able to hit the menu. Have you tried playing again and experienced the same issues or have you found some sort of fix?
@Wakapeil: Yeah, I figured it out right after posting. I'm at the PC and those achievements are freakin' brutal, but like you said 360 ain't exactly easy either. You still have my permission to be a golden god, sir. Personally I only got two S-ranks, one for Uncharted 2 and the second for something that is just really dumb.
@SSully: I think that might be a bug, yes. I've played through this game two times already and have never encountered such an issue with the any of the previous versions. I haven't tried the 2.0v so I can't say for sure though.