Well it sounds like your SMC was corrupted by the reboot, so use a new one, or find a way to do a recovery/low level format on your existing card.
After that, you need to determine why your GP32 rebooted so it doesnt do it again. Did you have it plugged in? If so the plug may have wiggled lose enough to cause a quick reboot. If you had batteries did they have a decent charge? To keep your GP32 on, the FLU on, and transfer files from your PC, requires a decent ammount of juice to run and it could be that your batteries were just not up to snuff to handle all of that at once. When installing software onto your GP32 via the link cable, its a good idea to turn the FLU off to save some juice (if you have one that is).
If you are semi electronically inclined you can pull the GP32 apart and check for loose / faulty connects for the hot and ground for your batteries (or possibly your FLU).
If you get your GP32 repaired, replaced, whatever, you are still stuck with the problem that your SMC has most likely been corrupted. This will happen if you use any kind of writer and you write to nearly any kind of media, and turn off your hardware / remove the media during the write proccess. That is why readers that you plug into your PC have the little "Read/Write" light so you can wait untill its complete before trying to remove it.