Silverlight error - Async_ExceptionOccurred (Internet Explorer fails, Firefox works!)

Hi,

I wonder if anyone can help. I have a silverlight 2 app which runs fine in IE and Firefox on the dev environment.  However, once it's rolled out to test on IIS we get problems with it calling the webservices.  This is just failing in Internet Explorer only.  Everything is fine in Firefox.

When a page loads, it fires off to the web services and gets various bits of data to populate the form.  It seems it will decide to complete some requests and not others.  There isn't any particular pattern to which calls it will fail and which it won't.  It very intermittant.

All the errors are like this

Message: Unhandled Error in Silverlight 2 Application [Async_ExceptionOccurred]
Arguments:
Debugging resource strings are unavailable. Often the key and arguments provide sufficient information to diagnose the problem.

All clientaccesspolicy files are in the correct place, all the service references endpoints are ok.  It's very weird!

Has anyone ever experienced this?

Regards,
Nicky