Excel Services does not work when empty root site collection

Hi,

The scenario is:

- I have one site collection at http://sharepoint/sites/site1 .

- http://sharepoint/ is empty (no site collection).

Excel Services does not work on this scenario.

The error on the server is:

An internal error occurred.
   at Microsoft.Office.Excel.Server.MossHost.MossHost.Microsoft.Office.Excel.Server.Host.IEwaHost.IsSecureConnection()
   at Microsoft.Office.Excel.WebUI.EwaCUIDataSource.EnsureDocument()
   at Microsoft.Web.CommandUI.CUIDataSource.RunQuery(UIQuery query)
   at Microsoft.Office.Excel.WebUI.EwaRibbon.QueryRibbonDataSource(CultureInfo uiCulture, String clientID, Boolean denormalizeImareUri)
   at Microsoft.Office.Excel.WebUI.EwaStringsHandler.ProcessRequest(HttpContext context)

On the client, it just gets stuck on loading animation.

Is there any way to fix this, without creating a site collection at the root? Also, can I create an totally empty page at root?

Thanks.