How can I undo a first installation on my computer?

[COcz]

Are you sure the computer does not know when the nook is pluged in? Windows? What kind? Are the laptop and desktop both the same? Can you only "authorize/register" the nook on one computer? I'd check it out in the control panel/device manager. From there you should be able to uninstall drivers. I know nothing about nooks, but just making it connect should be straightforward.