Thread:Project:Support desk/HTTP 500 error after "Save" and before showing "Login-page"

installed software versions: - Windows Server 2003 - MediaWiki V1.18.2 - MySQL V4.1.14 - PHP V5.2.12 - Microsoft-IIS/6.0

The software was installed as default in German. There was no installation error.

Whenever I edit a page and than click one of three buttons at the bottom (e.g. Save) I get a "HTTP 500 Internal Server Error". But when I get the error page I still have "http://DNS-Name/wiki/index.php?title=Hauptseite&action=submit" as the address of the page in the browser. When I open "/wiki/index.php?title=Hauptseite" manually after this all changes have been written to the database.

The same error occurs every time I click on "Log on/Create user Account" (which links to /wiki/index.php?title=Spezial:Anmelden&returnto=Hauptseite) and the Logon-page is never shown. Even if I write "http://DNS-Name/wiki/index.php?title=Spezial:Anmelden" into the address line of my browser I receive this error.

What can I do? Where should I look?