On 17 Mar 2002, at 15:14, Ian wrote:

> Immediately prior to a reboot, there's a little 'Fssst!' noise,
> very brief and only audible because I have the PC alongside me on
> the desktop with the side off the case.

  I think this is an important clue.  It suggests:

1.  A momentary burst of electrical noise on the wires to the case
speaker, or

2.  A momentary burst of electrical noise on one of the connections
to the sound card, or

3.  A momentary burst of electrical noise on one of the connections
to the modem, or

4.  Some kind of arcing or capacitor discharge, with moderately high
voltage.  And about 90% of the stuff inside the *case* that ever
deals with >12v is inside the power supply, that's where I'd look
first.

David Gillett

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