It confirms that Rails is handling the request, LSWS just relay the response from rails.
You can try killing all ruby processes, so if a ruby process cache the rhtml, it will be flushed when next request comes in and LSWS start another set of ruby processes.
To find out what happened in Rails, you can strace/truss the ruby process, it will show the system calls for serving that request. For rhtml page, you will see related system calls operating on the rhtml file.
Same solution for the other problem, strace the ruby process that serving the request will show what went wrong in rails.