In an effort to optimize resources in IIS 6.0, an ISAPI filter is not loaded until a request is made to a Web site that requires the ISAPI filter. Until this request is made, IIS Manager does not display the status of the ISAPI filter. Also, if the ISAPI filter requires the SF_NOTIFY_READ_RAW_DATA filter notification, the filter will not load while IIS is running in worker process isolation mode. Review the Application Event Log for events from W3SVC-WP to verify that the filter did not load. To remedy this problem, run IIS in IIS 5.0 isolation mode or contact the vendor of the ISAPI filter for compatibility updates.