WARNING: I strongly suggest copying your phone's SD card contents to your computer before performing the NK1 upgrade. I believe the NK1 upgrade corrupted the files on my SD card. Yesterday, I mindlessly did the OTA upgrade to NK1. All seemed OK until I tried to access the SD card today - it was not present! So, I pulled the micro SD card out and inserted it into my PC, and it said the card was corrupted. I put the SD card back into the phone and formatted it, then successfully exported my phone contacts to the card to verify it was working. Fortunately, I had stored only contacts and music on the SD card.