I remember someone saying they had a problem with SD cards failing on their Hero and I think I know what's going on. Today I had the SD card failed issue and it was my second one since getting the phone on Dec 26th. I think I narrowed down the cause. Both times, this happend right after running on the treadmill with my Hero in my shorts pocket. The first time, I formatted as suggested, losing all of my pictures, mp3's, etc on the phone (luckily I always backup). This second time, I was going to put the card in my computer to see if it was indeed broken. The computer read everything fine so I stuck it back in and it worked. I think what it happening, it something is making the card move around in the phone (in my case running) and causing it to not be able to be read properly. I only suggest pulling the card out and reinserting it before rushing out and getting a new card. Hope this helps a bit.