Enable Anonymous Authentication on the OfficeScan server to resolve the issue:
- Select the OfficeScan website under Sites in IIS.
- Select "Features View" on the lower part of the window.
- Double-click Authentication.
- Right-click Anonymous Authentication and select "Edit".
- Select "Specific user" and then click on the Set button.
- Type in the administrator username and password, then confirm the password in the text boxes.
- Click Ok.
- Restart World Wide Web Publishing and Officescan Master Service.