IE 10 Compatibility Type and Document Type

Hi Folks

I'm kind of stumped here with IE 10 (on RETAIL Windows 8, the Windows 8 developer preview from September 2011 works fine in IE 10).

I keep getting a "Document Mode" of IE 7 in IE 10 on a RETAIL Windows 8 PC (once I hit the login.aspx page)

I've followed this strategy (to the letter):

http://msdn.microsoft.com/en-us/hh779632.aspx

The only thing I have left, which has a DocType declaration, are 3rd party vendor controls (i.e. Infragistics and FileVista), and these are buried deep in the site.

Any thoughts or experiences?

Thanks
Rob K