Because it has failed to connect with a "time server". Power down and then power back up and it should have cleared the old date and time, and now have correct date and time.
its not that simple. apparently there is no time server on the web side to talk to and if smc doesnt offer a customization utility youre screwed
2008-11-09 07:37:20
Ha, this is not the case as mentioned many times in the forum. there appears to be bugs in the firmware, for example, with the wb7904wbra2, none of the firmware will get u the right time and date.