The level Keyes in Halo CE is broken. It says I beat it on Legendary, but I did not I actually skipped the level thinking that I had played it, because it said that I had beaten it. So, me and my buddy went through and beat it thinking that it would be all good then, but no dice. It isn't even taking score or time, not even letting switch the filter from old to new to get that achievement. It's the entire level. So, from an achievement stand point that sucks.
The other weird thing is that I played the entire first and second game on 2 player. None of our stats transfered to the second player. Like if he signs in it's like he never beat the levels, which is no big deal, I think, at least, I haven't seen where it would be a problem, he got his achievements. Whats weird is 2 levels in the second game show completed to him and none others and it's like I never beat just those two. It's all very bizarre. Just letting you know!