I'm actually a little surprised this hasn't come up sooner.

If you have an Xbox LIVE Gamertag which is tied to an e-mail you don't often use and is set to expire after a certain period of inactivity, i.e. Hotmail (for example), then you may want to log in to that e-mail as soon as possible. Otherwise, you could be kissing your Gamertag, along with all the Achievements and such tied to it, good-bye.

The problem comes from the Windows LIVE ID e-mail address required to set up a Gold membership. If the e-mail expires due to inactivity (likely due to users actually using alternatives like Yahoo! or Gmail for their day-to-day business), the e-mail is deleted, along with any Gamertag associated with it... even if the user has set up additional non-Hotmail addresses since signing up.

On a related note, I did learn myself the hard way that they will retain the login info for the account for you, but its contents will be entirely wiped clean if you reinstate the account. But this was some years ago, and I'm unsure if that is still the case.

A customer service representative for Microsoft has confirmed the problem, apologizing and noting that "the only alternative is to set up a new Gamertag with your preferred email address." She added that even with the users having an up-to-date, accurate profile on their Xbox 360 hard drives, the achievement points would still be lost due to their non-transferable nature.

And presently, there is no way around the problem.

As for Silver members, this does not affect their offline membership, but it can prevent them from becoming Gold members, which would allow them to play in multiplayer matches online. Additionally, Marketplace downloads seem relatively unaffected, and are diagnosed by the "8015d080" error code when new subscription attempts are made.

When GamesIndustry.biz sought to get comment from Microsoft on the issue, they only offered the following:

"We are investigating this issue and don't have any further comment to make right now. Any consumer with any issues regarding their Xbox 360 or Xbox Live account should visit xbox.com/support or call their country's customer support number." -- Microsoft, to GamesIndustry.biz

The loss of Gamertags has been a bit of a sticky issue with Microsoft for some time now, hopefully this will be impetus enough for them to improve their system.