When you try to open the Incidents Tab or the Incident Settings (under Configuration Tab>Server Settings>Notification Server Settings) pages, you get the page saying 'Page cannot be displayed'.
When you look on the NSRedirect (under IIS manager>Web Sites>Default Web Site>Right-click Properties>ISAPI Filters tab), it has the Down status (Red arrow down) and Unknown priority. If you restart IIS, it comes back to Up status but if you go to the Incidents Tab or Incidents Settings page, it goes back to down status.
Looking on the Events Logs, under the Application Logs, you may see errors like these ones:
Event Type: Error Event Source: W3SVC-WP Event Category None Event ID: 2268 Date: 10/27/2006 Time: 10:14:57 AM User: N/A Computer: AltirisServer Description: Could not load all ISAPI filters for site/service. Therefore startup aborted.