I'm not an ace scripter, but this might help.
In game_actor, lines 576-584:
CODE
#--------------------------------------------------------------------------
# * Change Level
# level : new level
# show : Level up display flag
#--------------------------------------------------------------------------
def change_level(level, show)
[b]level = [[level, 99].min, 1].max[/b] #<--------------RIGHT HERE
change_exp(@exp_list[level], show)
end