[TheMamba]

Oh man...I had a similar thing happen with one of my USB joysticks and it drove me nuts.

Here's a couple of ideas:

Are the other external devices plugged into the USB when you try to plug in the DVD drive? Try unplugging the others and only plugging in the DVD drive.

Drivers - check to see that the drivers for the DVD drive are installed in XP. While you're at it, check to make sure you have the most up to date drivers.

What I would probably do is uninstall any drivers associated with the DVD drive and then try reinstalling the DVD drive as if it was the first day you purchased it. Hopefully you still have the instruction booklet that came with it. Follow those directions to a T. You could also check on the BenQ website and see if they have the procedures for un-installing and re-installing there.