In this post I had a little problem with Reporting Services.
I didn't have time to investigate it a little deeper until a couple of weeks ago. The problem is that there is no real solution for the time being. Even SQL Server 2005 Reporting Services experiences the same issue.
So I finally decided to submit it to Microsoft Support. They have confirmed that it is a bug in Reporting Services and the developers are looking into it. Let's see how they fix it ;-) I'll keep you posted of course.