Not a noob error. SD card was working fine (on .602), then during music playback a couple days ago it started hanging up, then just stopped. DX says the card is unmounted, has errors, etc. If I try to format the card in the DX when I get an error message, it fails to do anything. When the DX is plugged into my PC via USB cable, the card shows up as a drive in Windows explorer, but is not readable (get "insert disk" error in Win Explorer). SOOOOO, I swapped out the card, got the exact same error. Both card read just fine in PC. The SD cards are good. The DX was reading them just fine for over a year. Now it can't see them. Any ideas?