After you uninstall Microsoft SQL Server 2008 Reporting Services Add-in for SharePoint Technologies, you may notice that you are not able to browse SharePoint pages in a non-default zone.
When you uninstall the Reporting Services Add-in, some of the configuration settings related to Reporting services are not removed from the SharePoint’s Web.config file due to an underlying issue with SharePoint technologies and Windows SharePoint Server (WSS) 3.0
You can avoid this problem by downloading and installing the following hotfix for SharePoint technologies before you uninstall the Reporting Services Add-in.
952288 Description of the Windows SharePoint Services 3.0 hotfix package: May 8, 2008
If you had already uninstalled the add-in before applying the hotfix discussed above, then the only workaround available is to manually remove the additional tags that are associated with the non-default SharePoint zones in the SharePoint’s Web.config file. You need to do this for each server in the SharePoint environment.