I would double check to see that the ACR file is in the correct location, and there
is only one file there.
What happens when you open bridge and navigate to the folder containing the raw files?
One thing that frequently clears this type of situation -- try: Tools > Cache > Purge Cache For Folder "images"
Another is to reset Bridge preferences: Hold down the Ctrl key while starting Bridge
Thanks for your suggestions - I made sure I had only one camera raw file and that the latest plu-in were installed. After reading the support sites I finally was able to get it working very simply - going to View and then Show Hidden Files; that worked!