Thanks for your post and sorry you're experiencing issues.
I've seen this behavior in one other case but we never reached a very good conclusion about why it was happening. Are you using IIS or the built-in web server?
The other customer was able to fix the behavior by re-installing the built-in web server, so that's my first suggestion. If that doesn't help, it would be great if you could send your log files in (just reply to the auto-email you received earlier today with the ticket reference). You can find the log files in configuration>about by clicking "retrieve all log files".