what log files should I be looking at to resolve this?
servletd log files should be a good starting point. Try looking in there first and see if you find anything obvious. Also do you have any externals / controllers or any AJAX type of stuff in your components? If yes, make sure that is valid and returning what you are expecting it to return and not hanging somewhere.
Bad Site PreController, was expecting to see an error message like the page preview environment throws. threw me for a loop until I decided to see the page preview and followed the stack