I see a minimalist black-and-white page written in Cyrillic characters that is in dire need of an translation into one of the supported languages. The defaultwebpage.cgi is usually because of caching, but that is probably not the problem if you've seen the site before on the same machine. An HTTP 500 response without further information tells me nothing (other than that your site is not giving away dangerous information when it fails). It may have just been a temporary glitch at the server, but if that temporary glitch has caused the default page to be cached locally (or worse, at your ISP) again, then you may have to delete your cache and history locally or wait for the page to age out of your ISP's cache.