Are you sure that it happens only after sending fax, are you seeing any
crash window before reboot.
Is any event logged in the system (type eventvwr in the run window).
Also can you check sending fax after disabling fax status monitor.

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Loganatr [MSFT]
Microsoft Printing, Imaging and Fax Team
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> Now when I sent a fax after the fax monitor says the 'call
> is completed' the computer reboots. When this occurs the
[quoted text clipped - 7 lines]
>
> Paul