I own a 60GB Passport and had the same problem. My computer would not recognize my Passport drive and other devices.
After trying several computers, cables, usb ports I finally ordered an Ultra USB 2.0 all in 1 card reader/usb hub.
In my opinion the problem with the Passport is that its voltage requirement is on the high end of what a regular usb port can provide.
Mine would work intermitently, depending on how many devices I had plugged into my usb bus.
By purchasing a USB hub that has its own power supply I finally got consistent performance out of my Passport.
