I have a Dell XPS 1640 laptop running Windows 7. Unfortunately, when I type "ipconfig/all" from the cmd prompt, my physical address displays as "00-00-00-00-00-00-00". How do I correct this problem? I'm told this is a software problem, but am seeking help. Dell wants to charge me to fix it, which is terribly unfair since I received it in this condition. Any assistance you can provide will be greatly appreciated.