FYI: Using Mac system 10.9.5, Chrome browser, I get 500 error on entering site and on clicking any internal link, all remedied by refreshing the page. BUT I do not get an error using the search engine and clicking on links it brings up or any subsequent links.

So I guess that's a workaround for me: Open the site, refresh, search for something, go back to the main page and it's all good from there on.