When trying to print I get this error. What does it mean? How can I diagnose it?
This question can't be simply answered. It usually means that something with your printing device driver is messed up.
Any additional information?
Most likely you are using CUPS.
Did you have a look at the logfiles? /var/log/cups/ ?
Maybe this will help you, to specify your questions.
Try to do some printing at a low level to eliminate any error sources with some applications. Have a read through the manual: http://www.cups.org/documentation.php especially at "Command Line Printing" http://www.cups.org/documentation.php/doc-1.4/options.html
This will give you some basic diagnostic tools.