The other guys mentioned scripts from mods being still on your save after disabling the mod...Sucky option but maybe you should disable all your mods(or at least the ones that arent popular enough that you can say they have a good reputation) and play a new character to 25. Sucks to lose your character though... Is it exactly level 25 that is the problem? Prehaps it's more of a gameplay hours thing like that refID bug in Oblivion...
Maybe you should try leveling a character up in with console commands(PC exclusive cheat codes) and see what happens...
Maybe you should try leveling a character up in with console commands(PC exclusive cheat codes) and see what happens...