Mr Anderson,
Do you have a solid red light on it? Usually if a restore works the MUD is OK and is communicating properly. Some machine just can't boot from USB or require you to change the BIOS settings. You can also try booting from the CD and locking to the USB Key.
The MUDs can fail so it may be time to get a replacement. First try it in a machine you know it has worked in the past on. If it still does not work contact tech support and they will arrange getting you a replacement.
The most efficient procedure is to fill out a tech support form requesting an RMA. Once we determine it is bad a RMA number will be issues. Then you ship back the broken one and when we receive it we ship out the new one.
Here is a link to the tech suppoer form;
http://www.pc-doctor.com/support.phpPlease fill it out, make mention that you posted on the forums and we'll get you going again as soon as possible.
-Fred