Crossdomain.xml request delayed FMS 4.5

I am using FMS 4.5.

When I open my page, sometimes the crossdomain.xml is downloaded automatically, but sometimes the GET to crossdomain.xml become pending and take something around 5 minutes to finish the request.

The flash player are on another server, and call a HTTP request

My problem is similar with that one  Crossdomain.xml request unanswered by FMS 3.5 Application