Bridge 2.x, the one that comes with CS3, is easily the worst piece of software ever released by Adobe or any other major company, in my view. It should have been fixed for free, but it wasn't.
Cache management is extremely poor in Bridge CS3. Purge the Cache for the offending folders through the Tools menu in Bridge. DO NOT use the global purge command in Bridge preferences.
Fortunately, Bridge 3.x in CS4 is much, much better.
Thank you Ramon - much appreciated!