Sharepoint Error Viewing Site Content and Structure Reports

Another weird Sharepoint error.  Suddenly our MOSS site started throwing errors when viewing reports in the "Site Content and Structure" screens. 

 

The default "All Documents" report was fine, but others such as "Checked out to Me" gave this helpful error:

 

Exception occurred. (Exception from HRESULT: 0x80020009 (DISP_E_EXCEPTION))   at Microsoft.SharePoint.Library.SPRequestInternalClass.ReleaseResources()
   at Microsoft.SharePoint.Library.SPRequest.ReleaseResources()

 

Simply adding "<Lists ServerTemplate="850"/>" into the CAML list type for the report got everything up and running again

 

I've no idea what caused it but many thanks to this forum post for the cure!