To Whom It May Concern: 
 
I've encountered something really bizarre that I have not found in any other forum, FAQ, support page, etc. In Half-Life 2: The Orange Box, for the Xbox 360, I played through Episode 1 offline and got "The One Free Bullet Achievement". Unfortunately on that same console, before I could log back online, I lost my gamertag and any achievements that I had accumulated while offline. I was then able to get online, recover my gamertag to that same console, and begin playing through all of Episode 1 again to regain my achievements. So far everything is going rather well, however here is where the issue lies. I have been unsuccessful in obtaining "The One Free Bullet Achievement", not due to a lack of trying, but due to some major glitch that has occurred within Valve's own achievement monitoring system.  
 
You see, when I view my achievements via the Xbox Dashboard, it claims that I have not obtained "The One Free Bullet" Achievement, that's rather obvious, since it has no memory of me obtaining this achievement. However, when I go into Half-Life 2: Episode 1 and view the achievements in-game it claims that I HAVE gotten "The One Free Bullet Achievement". I believe this to be the reason why, despite numerous attempts playing through Half-Life 2: Episode 1 again, making sure to only fire one bullet at the padlock in the second chapter, I have been unsuccessful in obtaining that achievement again, at least in terms of Achievement Points/Gamer Score.  
 
I understand that this is by most standards, a non-issue, as it does not break the game or stop me from enjoying the greatness that is Half-Life 2: The Orange Box. However, I still consider a bit of an inconvenience simply for the same reason that people get angry if they lose their high-school diploma, or award certificate, it's not completely necessary, however it's still a representation of a feat that they have accomplished and would like to be able to get it back. If any of you esteemed Giant Bomb forum viewers have any insight, assistance, help, guidance, or anything else that you can provide I would greatly appreciate it and would be eternally grateful.  
 
Sincerely, BenKweller57

Nevermind, I was able to solve the issue finally. All that was necessary was to delete the current Episode 1 save file on my harddrive and then have the achievements sync back up with the Microsoft achievements to establish those that I had done, and hadn't done. Went through last night and now have 100% Half-Life 2: Episode 1. Hooray!