Hi Janet,
First of all you do not say what version your operating system is win98 win2k winXP.
Secondly you do not say if the external unit was working then just stopped working
Thirdly you have not made it clear if the external drive has ever been installed on the PC you are now using
Irrespective of your operating system if problems have developed recently then either the external drive could be at fault OR the usb drivers / interface card on the PC you are using
If you can supply more info I will try to help
Regards
Dave Rawnsley @ Media Magic Computers, Leeds
Engineer @ Media Magic Computers, Leeds, October 2005