HP Color LaserJet 3800 50.2 error printing envelopes Tray 1

We have an HP Color Laserjet 3800 that has recently started erroring out with a 50.2 error whenever the user tries to print to envelopes in tray 1 with either USB connection or networked. The unit works fine when using any tray with standard Letter paper. When a print job is sent for an envelope in tray one the unit will show ''processing'' for 1-2 minutes prior to erroring out with the 50.2.