You should verify that the server certificate is valid. If it is not valid, you can try reinstalling the certificate or installing missing certificate chains.

1. Open Internet Information Services (IIS) Manager.
2. In the console tree, expand the computer name node.
3. Expand the Web Sites node, right-click Default Web Site, and then click Properties.
4. On the Directory Security tab, in the Secure communications section, click View Certificate.
5. Verify the following in the Certificate dialog box:
   1. On the General tab, confirm that the certificate is valid.
   2. On the Certification Path tab, verify that the Certificate status box contains "This certificate is OK."

      If the certificate status is not OK, you will see a red X or a yellow warning icon. If this happens, try reinstalling the certificate or the certificate authority root. For more information, see the "Troubleshooting" section at the end of this paper. If you received the certificate from Microsoft Certificate Services, ensure that the certificate has a .p7b extension. If the problem persists, contact your Web server administrator.

   3. Click OK to close the Certificate properties dialog box.
6. Click OK to close the Default Web Site Properties dialog box.