For Simon above
My original file was a 32 bit merged HDR file created using CS5. THe export peferences are set to send a 16 BIt file to CS5--that is what will not open.
I got around this by sending the file to another plugin which did open, made a small change and saved back to CS5. THen I sent to CS5 which did open, made more changes and aded some layers an saved back to LR.
Today I discovered that somehow, the size in inches of image changed slightly, the resolution was 240 instead of 300 I specified in Preferences, and the the bit depth changed to 8 bit instead of the 16 bit I specified.
I have no ideal how these changes occurred.
Is Lr becoming unstable?/ How best to deal with this?? I am On a MAC using LR 4.2