A client has a WordPress 2.1.3 site hosted by Network Solutions. They sent a notice that they are upgrading to PHP5 from PHP4. They included a test link that allows one to see how this will affect your site. All links from the home page (and who knows, possibly internally, too) fail after the upgrade. (For fun check it out at: http://www.webhostinguserguide.com/05-unix_php_notice.htm)
I suspect that the fix is easy, but I don't know it. Can anyone help?