It could simply be your connection.
While USB and parallel connection are usually pretty secure, they can sometime work their way out of their ports. Sometimes devices get moved around, wires get stepped on, and even computers sometimes get pushed around. So when something goes wrong, one of the first things you want to do is check your connections and make sure they're secure.
And that they're clean. Because the back of your computer -- and, sometimes, your printer -- can be a jumble of wires, there is sometimes an understandable tendency to pass it by with the duster. Which is fine -- except that dust can get into connections, and can occasionally interfere with your connection. So another thing to try is to use some canned air (you can get it any most electronic stores) to blow any dust out of your ports before you reconnect.
Of course, your problem may have nothing to do with a loose or dirty connection. But it should be the first thing to try before you start dialing tech support.
