If you are getting this error "ReportServicesConfigUI.WMIProvider.WMIProviderException: The report server installation is not initialized."
Means that for some reason ( usually because of an upgrade, or a change of the physical location of the reporting services folders ) the report server was deactivated.
To initalize it, go to Start-> All Programs -> SQL Server 2005 -> Configuration Tools -> Reporting Services Configuration
And then, go to the Initialization tab. Remove all the items there and then press initialize, reporting services will insert a new one that is working good by default.