Have you run the update_oztivo command, or used the remote key sequence clear, 9, 2, clear to update the software? If not, do so.
Have you rebooted the TiVo a few times? If not, do so and ensure you are not still stuck in Maintenance Mode.
Do you run a router/firewall that has port 37 blocked and therefore the TiVo cannot access the clock setting server? If so, open the port in your router/firewall.
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