I took a SD card (4gig Sandisk Extreme III SDHC) out of my computer, and back into my camera, and I instead of a shot count in the LCD on the top of the camera, I got the letters CHA. What the? I headed to google, and “d90 CHA” brought back a ton of hits. This was not some weird isolated incident. Most were saying it had something to do with the memory card, and that if formated in camera, it would correct it’s self. Since I always format every time I put the card back in, that’s what I tried to do. I usually use the shortcut buttons, but they didn’t work. I then went to the menu, and it the camera seemed to take a long time to format. When it was finished, I still had CHA in the LCD. I took the card out, put it back in, and now the shot count said there were 27 pictures left. Weird. I tried the format again through the menu, and this time it only took a second, and appeared to work. We’ll see how this card holds up. I should mark it so I know which one it is.