Help please- Lion wont recognise Nikon RAW files [nef]

Hello all, posted this issue on a number of forums to no avail - basically been using my iMac with Lightroom to download and process photos from my Nikon D300s and D90 for over a year - then I upgrade to Lion and it all stops [no other changes]. Now the D300s isn't visible at all and the D90 is visible but only offers the chance to "save" the NEF files elsewhere. Having been forced to download my NEF to an old mac mini and into iphoto I know its not the cameras, the cable or the memory card. I have checked I have the most upto date software on the cameras and the latest version of lightroom so it would appear Lion has either messed up some settings or Lion can't cope with NEF files - can anyone help this is really maddening! Thanks in anticipation