xWiki and IIS with Jakarta ISAPI Redirector - 401.5

xWiki will not display logon page when used with ISAPI connector on IIS. 401.5 Error.

Tomcat itself seems to be working ok with both teh examples and manager apps all working. xWiki redirects to the logon page but IIS displays a 401.5 error instead of the logon box allowing you to logon.

Strangely if you logon through :8080 (tomcat direct) then refresh the IIS page it will use the logon ticket with no issue until you logout at which point you get a 401.5 error again!