There been a long-standing issue, ever since IE 7 was introduced, related to GPMC and the use of IE Maintenance Policy. Specifically, if you defined zone security in IE Maintenance policy from a machine running IE 7, and then tried to view a settings report on that GPO from GPMC running on Vista or XP (and presumably also 2003), you would get the following error on the Report tab:
An error occurred while generating report:
An unknown error occurred while the HTML report was being created.
XP would also throw this error if you tried to view an RSOP report on a machine that had received this policy. Until recently, the workaround would be to only use Admin. Template policy to define zone security. Specifically, you can do this under:
User ConfigurationAdministrative TemplatesWindows ComponentsInternet ExplorerInternet Control PanelSecurity PageSite to Zone Assignment List
Well, I just loaded up the new version of GPMC that comes with RSAT for Vista, Sp1 and it appears that this IE Maintenance problem is fixed! Of course, all that means is that you know have to use GPMC on Vista, Sp1 if you want to be able to get correct settings reports for IE Maintenance Policy, but its something!