hi...
i have one casio fx-880p, and work well.. but today, give-me a error TM ERROR.. and i haven't acess to lib funtion and others.....grrrrrrr..
and find in manual a solution..
only you need power on, and press P button on back (with ON), after reboot, press all reset button on front. after this.. power off.. and power on again.. and voila.

it's work.
your data will be destroyed..

sorry