Hello,

as you can see in our system requirements (http://www.kentico.com/Download/System-Requirements.aspx), IE8 is not listed here yet. Since the official release of IE8 was few weeks ago, there was no time to test whole CMS in this browser. About compatibily of IE8 and current 4.0 version you can find more info here: http://devnet.kentico.com/Blogs/Martin-Hejtmanek/March-2009/Support-for-IE8-in-Kentico-CMS-4-0.aspx

Best Regards,
Radek Macalik