Philipp,
1. Are you using Cute Chat and Web messenger?
2. Can you tell me which page you have problems with?
3. Does the error happen in IE 6 or IE7?
4. Have you modified the UI layout?
5. If you have a screenshot, it will be easier.
asp.net Chat http://cutesoft.net/ASP.NET+Chat/default.aspx
Web Messenger: http://cutesoft.net/Web-Messenger/default.aspx
asp.net wysiwyg editor: http://cutesoft.net/ASP.NET+WYSIWYG+Editor/default.aspx
asp wysiwyg html editor: http://cutesoft.net/ASP
asp.net Image Gallery: http://cutesoft.net/ASP.NET+Image+Gallery/default.aspx
Live Support: http://cutesoft.net/live-support/default.aspx