You probably just need to clear the part program memory. I know there is a procedure for this, but I can't remember what it is. Maybe one of the other forum members knows ..
I know that you have to hold one of the panel buttons while turning on the control. The Fanuc 3T operators manual has a table of these "memory clear" operations. There is one for clearing all the parameters also, so please don't use "trial and error" here.
You may also have a battery that needs to be replaced, which can cause this problem.