A 11-year old autistic boy from Seattle found all of his achievements on Xbox Live reset and labeled as cheater since his scores were impossibly high.

However she was shocked to find that her son’s achievements screen was reset and he was labeled as a cheater, an accusation that has “devastated” her son. Zdenek revealed that she has contacted Microsoft, asking them to remove the tag of cheater but without any success.
Zdenek said that she will be canceling the Xbox Live subscription from next month unless Microsoft removes the cheater tag though the company has time and again reiterated that his scores were illegally tampered before clarifying that Jackson can continue to earn achievement scores in the future.
Source-Medindia