It sounds to me that you have a problem with the Drive. Please give Plextors website a look here:
http://www.plextor.com/english/suppo...ink_atapi.html
This is a link to the Blink Codes for the drive. Here is the Tech Support number to give them a call also. They should beable to walk you through some tests. Toll Free (US/Canada): 1.800.886.3935