I find it strange that you are having to use different versions of the DNG converter. The latest version of that program will support all cameras that are supported by Lightroom/Camera Raw. The only thing you might have to adjust is the compatibility option. DNG files should be compatible with any version of Camera Raw from version 2.4 onward. Download the latest version of the DNG converter and experiment with the compatibility option.
Thanks for the reply. I find it strange too. I am using Camera Raw 6.4.1 and DNG converter 6.4
Even if I run DNGs through DNG Conv. 6.4 the files are unreadable by PS, only LR can read them.
Have you tried trashing both your Photoshop and Bridge preferences? I'd also try purging the Bridge cache. If Lightroom can open the files it really sounds like an issue with Photoshop/Camera Raw/Bridge. As a last resort a full reinstall might be needed.