Hi *, the problem is solved. It was an NOW incompatible version of the AjaxControlToolkit. Greetings Tobi -- View this message in context: http://mono.1490590.n4.nabble.com/Problem-with-mod-mono-xsp-runtime-on-CentOS-5-4-5-5-tp2231149p2232794.html Sent from the Mono - ASP.NET mailing list archive at Nabble.com.