Since the new content for Fallout 3 has been coming out, I've been buckling down and, after alot of hurtles, have managed to get all 68 achievements in Fallout 3.

Are the achievements listed properly on xbox.com?

Edit: seems like you're missing Death From Above from Broken Steel, not the Vault-Tec CEO achievement. This happened to me also when I first downloaded the BS DLC and finished the first quest. Basically, the Xbox Live servers weren't all updated at that point so even though I got the achievement, it never showed up properly on my account. What I did was recover my gamertag and then replayed that mission, which caused the achievement to finally pop.

But that doesn't make sense. I know I got that one. When I look at the achievements on my 360, they are all listed as done. And whe I compare with others who have all 68, it says I do as well. This is irritating.

It's a known issue with Fallout 3 DLC content. Only way to get them back is to recover your gamertag.

So delete my profile from my hard drive and recover it? Then I should have all 68 instantly or I'll have to play through that mission again?

Got the achievement. Thanks for the help guys. I hope this doesn't happen with Mothership Zeta next month.

It happens a lot specifically with Fallout 3, Bethesda are known for bugs and glitches. Hopefully it wont, I never had it happen to me once with any Fallout 3 stuff, but they reccomend gamertag recovery to solve all problems. Sometimes you'll have to play to get the achieve again, sometimes not. Mostly not.