I've been using CS3 on an XPPro machine since CS3 came out. I've had and solved many problems, but this one has not changed since the first day: After converting a file from RAW to Tiff or PSD and working on it in CS3, when I return to Bridge there is only a generic icon for the file. No matter how long I wait, and whether the file is selected or not, no thumbnail or preview gets generated unless I purge the folder of its cache.

I use distributed sidecar files, and have done all of the usual tricks to cure this problem: I have purged cache files, purged what was left of my original central cache, trashed and regenerated preference files in Bridge and CS3, repair-reinstalled CS3 and Bridge, done uninstall/reinstall of CS3 and Bridge, and even changed my video drivers. I have tried hardware vs software acceleration. Many problems along the way have been resolved, but nothing has helped with this one.

Are the files that are not displaying over 200M?
As I think that's the default setting for Bridge not to render a file.
Just adjust to taste in preferences if that is the problem.

I have that option set to 400mb. But this happens with all of my post conversion files, ranging from 8mb to stitched panos at 350mb.