Date time problem on SigmarionII

Hi,

  I just installed NetBSD 5.0.2 on a Sigmarion II, almost everything
worked well except for a date time problem: every time I woke the
machine back from sleep, I got following warning messages:

  WARNING: preposterous TOD clock time
  WARNING: using filesystem time
  WARNING: CHECK AND RESET THE DATE!

  After that system date time was also incorrect(lacked behind current
date time), does anyone know why this happens? I googled for this
problem but didn't got too much help, could someone point me to some
helpful info? It's really annoy to set correct date time again and
again.

  Thanks in advance ;)

Regards,
Ying YIN