Xbox Live has just recovered from its recent connection problems, but it looks like Microsoft's online gaming service is about to deal with another serious issue very soon. As it turns out, a gamer lost an achievement under very mysterious circumstances.

So here's the long story short: a Guitar Hero 2 player was able to unlock the relatively hard 800,000 pair co-op achievement in Guitar Hero 2, along with the help of his bud. A week later, the achievement disappeared from his account. Knowing that he already unlocked it, he checked his friend's list and found that his bud still had the co-op achievement.

Alarmed, he called a Xbox Live support rep, who told him that Microsoft regularly rolls back and recovers part of their servers as part of their routine to get rid of Xbox Live bugs. However, there's a relatively simple fix: unlock another achievement in the same game, and doing so will update his account and re-register his missing unlocked achievements.

The fix sounds simple enough, but for this particular gamer, he'll still have a hard time doing so since the achievements that he hadn't gotten yet are very hard to unlock.