I know some people like to cheat (Like me) and Mod their gamerscore for various reasons. One of the problems with modding your gamerscore is it increases the account vulnerability which makes it easy to be corrupted.
Here I will explain how to uncorrupt your profile.
Solution 1:
Have a USB memory drive plugged into your Xbox and simply move your profile between the USB and the Xbox Hard Drive, this may or may not fix it completely.
Solution 2:
Sign out of your profile and hit "Recover Gamertag" This should fix your problem indefinitely, however you may lose some of your gamerscore in the process but it's not a huge deal.
If this helped you, add reputation to me, and I'll gladly add more tutorials.
If you have any questions, don't hesitate to ask.