I got a HP 7700 here that whenever I push the "Copy" button it tries to take the original from the Paper Feed tray instead of the scanner glass.
It used to work, but now it doesn't. Ideas?
I'm going to assume you're dealing with an HP OfficeJet Pro L7700, and not a Photosmart 7700. :)
It sounds like your ADF (automatic document feeder) is malfunctioning in such that the printer always thinks there's paper in the ADF tray. Broken/dirty/stuck input paper sensor perhaps?
Things to try: