This is exceptionally strange and has been going on for a while. From the admin side, if I change a password, it doesn't take. So, I have to go through the process again, after which it works.
This is annoying, but not a real big deal. However, now I'm getting reports that front end users are changing their passwords and then it's not letting them back in...so, it's become a problem.
What sort of caching problem might cause something like this - I don't see how it could be related to browser caching problems. Could it have something to do with smarty caching? Or might there be some other caching going on with the server?