I have an hp LJ4250 (I'm not sure the printer type matters) installed on an XP machine via USB (the ethernet port doesn't seem to work or I'd network it!!). The printer is shared.
I have a Windows 7 machine and have installed the shared printer on it.
I actually have two instances of the printer installed on the XP machine - one with settings for letters out of Tray 2 and one with settings for envelopes out of the flip-down "manual" Tray 1. The "letter" printer is set up so that Tray 1 is Not Available and Tray 2 is Letter and the default size is Letter. I keep envelopes in Tray 1.
The problem is that the Windows 7 machine wants to print letter pages on envelopes out of Tray 1. When I select Print and go to Preferences, Source is Automatically Select. That gets envelopes printed.
I have to manually change the Source to Tray 2 every time to get letter paper output.
Nothing I've found seems to fix this. The printer setups on the Windows 7 machine are the same as on the XP machine with the intended source tray specified. This "Automatic Selection" doesn't even do what one would expect!!