I have been hovering over this forum looking for ways to correct this problem.
I had to re-install photoshop cs3 and when I did that my camera raw was suddenly missing?? I followed some directions and re-downloaded camera raw 4.6...now instead of camera raw being missing I can open files in raw...I just can't see the thumbnails. One discussion said to check in the preferences of photoshop and if it has more than one listed then something is wrong and there should only be one. well...I checked that and you would know it....my photoshop has 2 camera raw's in the preferences??? but I have no clue where to check to clean that problem up???
Have you tried purging the cache in Bridge?
If that does't help, make sure hidden files are shown in Windows Explorer and do a seach for the plug-in file.
If you find two, delete both and then re-install 4.6 in the correct location as shown in the instructions.