1. Power on the 5360-023 and allow the unit to fully boot.
2. Power off and then back on very quickly.
The Cure: Re-flash the Modem: See file and instructions, which are available directly from SBC Ameritech at the links provided.
Another secondary source for the patch file is the attachment in this forum post.
The problem is caused by a 10/100 autonegotiation flaw. The unfixed modem works with some 10/100 connections and few, if any, 10-base-T ports. For some it works better to the the user's ISP's sites than elsewhere.