"paul" <paul@discussions.microsoft.com> wrote in message
news:0F6597FA-2BBA-4F64-951F-CED4DF15FEEA@microsoft.com...
> Please help.
>
> I have 2 Identical computers. One which had the WD Firewire my book
> attached
> and turned on all the time sp3 was installed has no problems re booting.
> The
> other which had the WD drive off during the sp3 installation will not
> reboot
> if it is later on at the time of the boot. Once xp up and running WD drive
> can be attached as normal but must be off for boot ups. Uninstalling and
> re
> installing sp3 with it on doesn't help still won't re boot with it on.

This is known issue with XP (it isn't necessarily SP3 that is causing this).
The exact mechanism seems to be obscure because I am not aware of anyone who
has pinned it down with any certainty. It has been conjectured that the
nature of the problem suggests that XP is identifying the external disk as
bootable when it isn't and, of course, can't boot from it. There are other
more esoteric theories involving non compliant USB hubs - but that doesn't
explain why firewire drives are affected as well). What the mechanism is,
at present, is anyone's guess, because I have noticed this happening with
external disks that I know don't have (or ever have had) master boot records
on them. Yet other XP machines work quite happily even though they are
configured to boot from external drives.

The only workaround that I am aware of is to switch off the external drive
when you boot or reboot (It isn't necesary to disconnect it). It can be
switched on again as soon as the Windows XP boot screen appears (the one
with the blue progress indicator on).