I have experienced delays in the use of LR 4. I would like to add one other issue to the mix and that is a severe delay in the importation of .dng files from both a Leica M8 an Ricoh GXR. I have no problems importing .nef files. I would have expected that the .dng would import as easily or easier (given its an Adobe standard). Any suggestions. Right now, I am still waiting for 12 files to import.