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Joined: Aug 2005
Hi, Hans;
sometimes it happens that old batteries have a voltage difference to the new ones that's enough to "hang" the calculator. You may start with the [ON]&[yx] pressed together: this is the first attempt to get the calculator back to normal operation after a [ON]&[-] memory clear.
If you get your Owner's Handbook and search for the Battery replacement text (appendixes) you'll also find some information about resetting calcualtor's memory. One of the most simple procedure is the hardware reset: a single, brief shorten in batterie's terminals. Yes, you get a piece of wire or any conductive material (a paper clip, as mentioned in the manual, may give you some trouble if bending it to fit in) and briefly, very briefly, connect both (+) and (-) poles of the batteries. As for safety precaution, do not remove the batteries: they will ensure no more than 4.5V will be present in their terminals, even if you have electrostatic charges in yor body, what could dammage your calculator. To be even safer, touch some GROUNDED metal parts before doing this.
Hope this helps.
Luiz (Brazil)