Try to recover memory?

[TravisE]

I can't say why the SD card contents would get lost, short of an accidental reformat or some sort of weird corruption. I personally never had that happen to me. I've always had it and Port 2 remain intact after a crash.

It's probably a good idea to avoid writing to flash when the batteries are low (earlier versions of the ROM would actually prevent this, but the most recent revision allows it). I use rechargable NiMH cells and keep a charged set ready to swap in as soon as the low-battery indicator appears in order to avoid any lost work from a sudden power loss. Another option is to plug the calculator's USB port into a device that provides power, at which point it will automatically operate on the USB-supplied power instead of the batteries.