Without seeing exact errors it is hard to tell but we did have to changed the report services permissions inside
rsreportserver.config to use the following
<Security>
<Extension Name="Windows" Type="Microsoft.ReportingServices.Authorization.WindowsAuthorization,Microsoft.ReportingServices.Authorization" />
</Security>
<Authentication>
<Extension Name="Windows" Type="Microsoft.ReportingServices.Authentication.WindowsAuthentication,Microsoft.ReportingServices.Authorization" />
</Authentication>
http://seer.entsupport.symantec.com/docs/317967.htm