John,

But I do remember that, sometimes - possibly always - if I left a USB
memory stick plugged into my XP system (a netbook), it didn't boot -
stopping fairly early on in the BIOS boot process.

Yesterday I was too focussed on the USB thingy being a true drive, and
that - as far as I imagined - a too-high power-draw would most likely be the
problem.

That was yesterday (do you see it coming ? :-) )

After this morning having tried a seperatily-powered USB enclosure (with a
full-sized drive) and getting the same problem, I "stepped down" a notch
"just to be sure", and tried the same with a fully empty, non-bootable USB
stick inserted, exactly as you described. And whatdoyouknow, it failed
booting too. :-(

There goes my idea about a power-dip being the most likely cause ...

The problem is that its not just *any* USB device that causes a problem, as
I've been using the laptop with a wireless-by-USB-dongle mouse & keyboard
for a while now (read: its not just an(y) USB-stack flaw).


And to make things even more interresting, I thought of *not* having it boot
by itself, but manually select the boot device (pressing F12 on the BIOS
start screen). And whatdoyouknow, booting from either now goes without a
problem, allowing me to access the HD and thus make a backup from any of its
partitions.

So yes, it seems to be something rather low, probably even BIOS level
problem. In other words, you seem to have been right on the dot (even
though it was a totally different piece of hardware ...). :-)

And as the problem even pops up with a simple USB memory stick I think I may
rule out any power-dip problems ...

Regards,
Rudy Wieser

P.s.
I also did some googeling, but have not found anything pertaining to this
specific problem (not even a "me too!" post). Odd.