My memory card (SD Ultra II, 15mb/s, 8G) that i was using in my Canon camcorder FS100 was full so i put all my videos on my pc, and when I erased the files from the memory card, it said that their was only 4 min of free space left. This seemed quite weird, so i formatted the memorycard with the FAT type, and afterwards, putting the card back in the camcorder, the camcorder didn't recognize him : "cannot read videos with this card. Reinitialise using only the camcorder". I guess i erased some files that i shouldn't have,
If you erased the images in the camera only it should be usable, but, you can contact Sandisk for assistance ? A Recovery disk should have come with the ULTRA II or maybe not, I use Extreme Viii 60Mbps in a Canon 5D mark II with no problems over 2.5 years.