Many Xbox Live gamers who attempted to sign into their accounts today likely found a foul error on their profiles: gamerscore and achievements had been wiped!
However, Microsoft quickly got to work and had all their support teams tweeting and helping out customers. Eventually, a fix was found, and now if you are affected you merely need to sign out and then back in, or you can try to re-download your profile. If the issue persists, ask @XboxSupport on Twitter.
Some have speculated that the glitch came about as a result of the recent Gamerscore increase for XBLA games.