Possible workaround:


In Reporting's web.config, make the following changes:


1. Change

<system.web>
    <compilation debug="true">

To

<system.web>
    <compilation debug="false">


2. Add the following <machineKey> section to the <system.web> section

<machineKey validationKey="AutoGenerate,IsolateApps" decryptionKey="AutoGenerate,IsolateApps" validation="SHA1" decryption="3DES"/>


Reference:

http://support.microsoft.com/kb/911722