After far too many hours, I finally solved this problem.
I can’t explain why one individual was able to print labels just fine to a new HP LaserJet 5500, while nobody else could, but it has been rectified.
When she attempted to print a label to the Laserjet 5500 using the Avery 5202 template, it would go through just fine and in the case the label wasn’t loaded it would request a 4×6 page be inserted. When trying to print to the Laserjet 4000, it would request Custom Paper if the label wasn’t loaded in the MPF.
When other computers attempted to print a label using the same exact template (or new from downloading it), the LaserJet 5500 would request an Envelope #10 and upon inserting a sheet of labels, it would go through but come out with no printing on it. When attempting to print to the laserjet 4000, it would request ‘Com 10’ sized paper.
The problem persisted even upon upgrading from Office XP to Office 2007. Office 2007 has a touted connection to the Avery label templates built into the application. Unfortunately this still didn’t solve the problem despite the ease of use the new feature offered.
Final solution: Add the 4″ x 6″ to the printer’s capabilities per machine and the problem was solved.
Go to Control Panel, Printers.
Single left-click on the 5550 printer.
Go to File, Server Properties.
Create a new layout named something like 4×6 and assign the dimensions of 4″ x 6″.
Save the form.
Printing the labels from the exact same template, exact same version of Word and OS, and the above being the only change made fixes the problem.
This solution was the final solution implemented to a machine where I did all my testing and it worked. It was also implemented at a machine where it was the only change made and the labels printed successfully.