Same problem for me. I have installed a Silverlight 4 (SL) app on our client's server. This application is accessed via the company Intranet. I have assigned the Browser role in SSRS (Home > Folder Settings > New Role Assignment) to the user under which the SL app runs (IIS > Application Pools) -- even tried assigning all Roles to this user. I have added the user group that all domain users are in to SSRS and assigned the Browser Role. Still, the first time a report is requested from the SL app the user is prompted for a login.

I am using Windows Server 2008 r2, Sql Server Express 2008 r2, client machines are Win 7 or XP (SP3). I have run into this in the past but it is now a HUGE issue. Any help would be much appreciated.

Thank you.