This is really a ZERO star review. I have used an old-style HP-12C for over twenty years and never had a problem. I used it through undergrad and two masters degrees, all in business, so my calculator got a workout. Despite looking a bit beat-up, my original HP-12C still works flawlessly. I was excited when the new 12C with ARM technology came-out (it is the one with two batteries). For the first year it was great and blazing fast but now it's not working well at all. Specifically: