There is a Camera RAW update that you do not have completely installed. Downloading and installing the latest update will solve the reading problem. As to the file name, the behavior is by design; the leading _ means that the file is tagged with the Adobe RGB color space instead of sRGB. If you don't like the file names, familiarize yourself with the batch rename function in bridge. I rename all of my files in the format YYYY-MM-DD_XXXX.dng where Y, M, and D are year, month, and day, and XXXX is a 4-digit counter of the shots taken for the day. It makes sorting images from multiple cameras in the order taken much easier, no matter what the cameras name the files.