For my experience using bridge along the last years, i suggest you do always these 2 things before posting help requests for it:
1. Rebuild the cache completely by restarting Bridge pressing CTRL (on Mac...?). A dialog appears, with 3 radio buttons. Press in the middle (Purge Entire Thumbnail cache). Some times it happens that for some reason the cache has been corrupted and freezes Bridge; If you have long-term builted cache, it could take sometime deleting all the cache.
2. Network: if you browse file outside your computer on a network, if the access of the external drives fail or are inconstant, Bridge can be trying to access it and you get the result you said: it white out...
There are also other reasons, but I advise you to update to the last version Bridge CC.