Hello everyone, I started a new account some days ago and I began my (new) career on Halo. Starting by finish all Halo games, and hunting achievements before playing multiplayer forever. Today I played on Reach and be suprised that I unlocked two achievements from Noble Map Pack wich I didn’t (re)bought yet. Is it normal? I’m afraid of being banned … Is there any risks? If anyone can help me I would appreciate it.
Note that I cleared my HDD before create my account because I don’t want to play or unlock achievements on things I didn’t (re)buy (like XBLA games or DLCs).
Thanks.
Is your new account part of a family pack with your old acount?
If so, I read something about everyone on the account (or same console) having access to the same DLC. More detail on xboxlive/gold family pack.
I don’t know how deleting your HDD might affect that (maybe DLC is stored in the Cloud or something).
Nope, my account isn’t so I couldn’t have any link with my old account. I don’t have the DLCs on my console and I don’t have the “right” to play it, that’s why it’s weird that I unlocked two achievements from the Noble Map Pack I didn’t download and obviously I didn’t get those on Noble maps, it was Reflection and a Forge map in Invasion. Hope there won’t be problems with my account in the future, I always respected Microsoft’s terms of use, developers etc …
It’s probably just a glitch, similar thing happened to me on Guitar Hero. You will not be banned, MS goes after the big offenders and normally doesn’t even look at your profile unless you are reported for achievement hacks.
The Noble achievements were somehow “unlocked” for everyone at some point and can be achieved with or without having bought it and on any maps. 
Ah thanks! I tought I was the only one with that problem. =)