User555306248 posted
See this KB article. I don't know if it will fix Chrome as well as IE8.
http://support.microsoft.com/kb/962351
There is some more information about the problem here:
http://weblogs.asp.net/bleroy/archive/2009/03/23/asp-menu-fix-for-ie8-problem-available.aspx
A comment to this blog entry says there is a CSS change workaround. It's very simple and I tried it, and it works for me.