Hello, where and how did you install Camera Raw. What version is it? Also, is Bridge upated? (help>updates)
Thanks for the quick response, Pierre-Etienne. Something very strange is happening, but first let me answer your questions. After I reinstalled PS CS6 on my MacBook Pro (whose HD I had just reformatted under Mavericks) two days ago, I got a message from the Adobe Notifier or whatever it's called, telling me that there were a number of updates available for my Adobe products. I downloaded and installed them; I think a Bridge was included. I got an error message concerning 3 updates, including Camera RAW, so I went and got them by hand. The most recent ACR version seemed to be 6.7, bundled with DNC converter 8.3, which I installed, and then this morning when I ran across the problem I wrote about I did a new download, this time of the latest stand-alone version of ACR. I believe it was also 6.7, but when I open a file now in Camera RAW it gives the ACR version as 8.3. A bit confusing. You ask, where? In France, where I live, but from the English language site.
Now here's the strange thing. I just came back from some very intensive work at an international conference, where over the course of 5 days I took almost 8000 pictures. I use the star sytem in Bridge to rate the pictures (in this case 0 to 3 stars). Within each star folder there are subfolders for the different days, and then sub-subfolders for the various events each day - all in all, quite a few folders. This morning I was looking at the pictures in a particular folder, and the phenomenon that I wrote about occured: no preview image. I just checked, and it turns out that that is the only folder out of over 200 so affected! All the other pictures open normally, in all star level folders, on all days, at all events. What an amazing coincidence!
So I guess I don't in fact have a major problem. I have a minor problem involving one particular folder. The only question remaining is why that particular folder, and could it happen again?
Thanks for your help.