I've read a lot of articles here about 8400 fan noise, but
haven't seen the following symptoms described. Before I call
tech support (it's still under on-site warranty), I'd like
to get some theories about what the the problem is.

If the two-year-old 8400 has been in standby or power off
overnight in a room that's roughly 50F or colder, when it
starts there is a grinding/whirring noise that sounds like a
motor bearing beginning to fail. If I restart a few times
the noise does not disappear. But if i let the high-pitched
grinding continue for ten or fifteen minutes and then do a
power-on restart, the noise is gone and remains gone so long
as the computer is operating at normal room temperatures.
The 8400 is in use all day every day and the problem has
become more persistent over a two-month period.

Has anyone had the same symptoms with an 8400? Any idea what
the cause might be?

--David