Consider the following scenario:
In this scenario, you incorrectly receive a logon dialog box.
Additionally, a logon attempt may fail and the website might not open if you do not have permission to access the IIS website.
This issue occurs because the Report Manager
page incorrectly references /images/blank.gif that is not handled by SSRS 2008 R2 and that is handled by IIS.
Cumulative update information
SQL Server 2008 R2
The fix for this issue was first released in Cumulative Update 6. For more information about how to obtain this cumulative update package for SQL Server 2008 R2, click the following article number to view the article in the Microsoft Knowledge Base:
Cumulative Update package 6 for SQL Server 2008 R2
Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2008 R2 fix release. We recommend that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
The SQL Server 2008 R2 builds that were released after SQL Server 2008 R2 was released
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.