If you are running Crystal Reports in an excluded directory on a SharePoint extended site, Crystal Reports will not build the report because certain browsers are not GZIP compliant (Internet Explorer 6.0 confirmed broken). To fix, open the MetaBase Explorer in your IIS recourse kit, browse to your site root tree and set DoDynamicCompression to 0. No restart necessary.

Summary: During the install process SharePoint sets GZIP compression to true (0) in the respective website MetaBase. Client browsers that are not fully compliant with GZIP will have problems with ActiveX controls as it related to Crystal Reports.