Passport shuts my Mac G4 down

I never had a problem with the Passport before until this morning, I tried to plug it into my G4 and it shut the computer down twice.  I already had a My Book plug in but have had them both plugged in at the same time before with no problem.  Any ideas would be much appreciated.


Do you have the same problem if you connect your drive to a different computer? Also if you connect any other USB device to your G4 you encounter the same issue?