check out this link...
http://www.sqlservercentral.com/columnists/drussell/sslcertificatesonsqlserver2005forreportingservices.asp
Particularly the comment
'Now, for the part that my boss did not believe four months ago. Remove the line above the ReportServerUrl entry for the ReportServerVirtualDirectory. These two lines are "mutually exclusive" according to a document on MSDN today. You will just have to imagine how painful it was to find this fact out before Microsoft told us."
I do not have the MS link referenced; but it's common knowledge now.
Thank-you,
David Russell
Any Cloud, Any Database, Oracle since 1982