"No paper" or "Wrong paper size" warnings

Even though it has successfully printed over 2300 documents in its lifetime, our magicolor is finally giving us problems. We recently had to get a new computer, and after a successful installation, everything was going well. We printed one page and then suddenly the monitor window popped up and told us that there was no paper in the printer. There was plenty of paper in the printer.

I uninstalled it, removed all traces of it from the registry, and reinstalled it. Then, we were able to print two sheets before the printer informed us that the paper in the tray was the wrong size, which is where we are today. It's the same paper we have used for over 2300 prints so far. What could be the problem?