Maybe the board is defaulting reported time to a specific time zone?
I last visited yesterday at just past 11:15PM (04/08/2011), yet it tells me I last visited at 00:15 (05/08/2011). I know that isn't true as I was in bed.
I'm guessing that although you have chosen to use the Eastern US time zone in your settings, the board is electing to report time last visited in uncorrected GMT???