A new version of the NGPSD firmware is available! This fixes a bug when saving out a ROM from the installed games to the SD card, where any game larger than 512KB / 4MBit would save incorrectly.
To install the update, copy update.dat to the root of an SD card and insert it into the NGPSD cartridge. Turn on the NGP console and press OPTION when the RetroHQ splash screen appears, this will take you to the recovery console. Follow the instructions on screen to install the update.