Hi, I'm new here; just registered.
I have a Korg Pa80 and am ver seriously considering getting a Tyros.
Anyway the reason I'm writing is I've had this problem finding USB and Firewire external hard drives using WinXP too, ie, the machine says the drive is there and working but I couldn't find it. The solution turned out to be that in XP MS moved the acces for finding and initializing HD drives. The solution, for me, was to go to "Start" then to "Settings" then to "Control Panel" then to "Administrative Tools" then to "Computer Management" and then to "Disk Management". There you should find Hard Drive in the Tyros where you can "initialize" or format it. I think "initialize" is actually a Mac term. Anyway, give that a try and, hopefully, it will solve your problem.
BTW, MS "expert help" support people didn't know that and after going through two of them I gave up until I found that in the instruction manual for a USB/Firewire adapter case I got to put one of my extra HDs in (it's a FireExpress case that I got at Fry's Electronics and it has worked flawlessly using both USB 2.0 and Firewire).
Tom
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Bigger is not always better
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Bigger is not always better