Good. You encountered a long-running, well-known (among this group) bug in the wwwthreads software, one that the developers were (so far) never able to track down. It is intermittent and we never found what caused it.

The only work around I've ever seen is to do the logout/login thing, but I wasn't sure if it would work for anyone else.

I've now gotten in the habit of doing the logout/login thing once a day so that the problem never comes back for me.