... but I've had two XPs experience this...
What exactly does this mean?
Two installs of XP on the same machine OR two different machines both running XP?
Whenever I've had this type of problem, (disconnect/reconnect), with an external USB anything
it has always been the physical USB connection itself that was the cause.
1) Broken wire in the cable.
2) Contacts on the plug are recessed into it too much and don't make correct contact to ones in the socket.
3) Contacts on the plug are too short(!) and don't reach the contacts in the socket.
4) Contacts in the socket have been bent by someone pulling out the plug at an angle.
5) Contacts in the socket are too short.
6) Connection from front mounted USB ports to motherboard has come loose.
7) USB port on PC too tight and plug not fully inserted.
Honestly, USB ports give almost as much trouble as the old serial ports.
Shades, I don't think that is the cause because even though my past external HDs had this problem, this one is a Western Digital MyPassport without a power supply plug and is using a different usb cable.
If you mean it's powered by the USB port itself, (ie. it's a 2.5" drive), then are you plugging in both
USB plugs at the PC end of the cable, (you need to do this so the external drive has enough power), before
you connect the drive ?
Also, motherboards with VIA chipsets are well known for not being able to supply full spec power to the USB ports. Any idea what make/model yours is ?
Dumb question, have you tried all
the USB ports ?
The fact that previous and current external HDDs are having this problem points squarely at the PC as being the cause.
Have you reinstalled the system between the time when it first occurred and it's latest occurrences ?
If you have, then unless it's specifically related to a piece of software you keep installing it's more than likely a hardware problem - either the motherboard or the USB ports themselves.