Earlier today a ConfigMgr Admin reached out for help regarding their reports in ConfigMgr 2012 SP1. They could run the reports fine from within the ConfigMgr console, but when they tried to view them in the web browser, they got the error: "The underlying connection was closed: An unexpected error occurred on a send."
After some investigation it turned out they had tried to implement a SSL certificate for the reports, but because of a broken certificate, the report server virtual directory didn't like it one bit.
Credit goes to fellow MVP Matthew Hudson, who's post at http://sms-hints-tricks.blogspot.se/2013/05/reporting-services-configmgr-2012.html was spot on with regards the final piece of the solution (edit the RSReportServer.config file).
Remove the broken certificate and configure the report server not to use SSL anymore. Removing the certificates are quite straightforward, just open the Reporting Services Configuration Manager console, select the Web Service URL node, click Advanced and remove the broken certificate. Then repeat the same operation on the Report Manager URL node.
After that you need to modify the RSReportServer.config file in the ReportServer folder (Located in the folder where you installed Reporting Services). Find the following entry: and change the value setting from 2 to 0. Then restart the reporting services node, and the reports are back again.
The working Reports virtual directory.