>Hi,
>
>I use some code to generate a number based on a PC's hard disk serial number and the MAC address. Recently, I have one client out of a couple hundred that this number changes on sporadically. I wrote a program to display what the serial number and MAC address are and the MAC address has changed from a couple weeks ago. The client says the NIC has not been changed.
>
>I thought the MAC address was tied to the NIC. What could cause this to change?

How are you fetching the MAC address?