That is a generic and extremely uninformative error generated by the
server -- it basically means the server experienced some unknown or
unspecified error trying to process your request and that it wasn't one
of the usual ones, like page not found. Sometimes it results from an
inaccessible directory on the site or a filetype the server isn't
configured to handle. For example, when I added a blog, I initially was
getting 500 errors and I had to instruct the server to correctly
recognize the filetypes used by Blogger.
Did you change the filetype / extensions of the pages when you updated?
Or exactly what did you do to update them?
Have you successfully updated this website on this server previously? If
so, have you updated / upgraded anything recently, like FrontPage or
your operating system? Have you installed any new software, particularly
firewall software? Or updated to Windows XP SP-2?
If none of these leads you anywhere, contact your host.
