You may find that some mass production drive copy systems produce a drive without a serial number or a group with the same serial number. I have a batch of Compaq systems purchased with Win98 preloaded and they all have a serial number of all blanks. If you reformat a new number is created, but the originals have no serial number.

>Is there a way to read the hard drive serial number. I'm planning to use it for a security system so the user cannot copy the app. to another machine.