Found is but not sure how to fix. When debugging I find that when service is actually being sent the rootUrl is
where rootUrl should be
so that the request made should actually be http://computername/nameofpage/ + relative url of httpservicecall
right now I guess its trying to make the request at http://computername/flash + /relative url of httpservicecall
Ok, got to shut Network Monitor off. Window > Network Monitor > (little icon with red O with slash ). That should be shutoff not a default of true IMO.
Can you please file a bug/ECR at http://bugs.adobe.com/flex/ against the Flash Builder project.
PS: Also, if you could please post the bug number here a few of us can vote for and follow the issue as well.