EZproxy for Windows Error select returned 10055

In EZproxy for Windows, if the error:

select returned 10055

appears in messages.txt/ezproxy.msg, then the most common causes are

1. Windows Firewall does not include EZproxy in its configuration.
2. Windows 2003 running at less than Service Pack 2.

When diagnosing this error, if none of this information helps resolve the problem, contact support@oclc.org for further assistance.