DotNetNuke redirects site root example.com/ to example.com/Default.aspx - why?

After moving a DNN 4.3.7 website from a Windows 2003 to a Windows 2008 server (IIS 7), entering the URL automatically results in a redirect to Default.aspx. 开发者_开发知识库When you create a Google sitemap, the root node is named "Object moved" which is ugly.

There are no HTTP Redirects added to IIS 7. We are using Helicon ISAPI rewrite, but there are no relating settings either.

It probably has to do with IIS 7 because we did not have this problem on IIS 6. On the other hand, other non-DNN sites on the same server do not have that problem, neither do other DNN-sites on other IIS 7 servers.

I am overlooking something obvious. But what?

Hopefully, you checked the Documents tab on the site in IIS. The "Enable default content page" might be it.

In Host Settings, there is a Friendly URLs section, which might also be the culprit.