Setup: Windows XP machine with a HP4000TN printer w/
envelope feeder.

This happens in both Office 2000 and XP:  

Recently, the function to print addresses on envelopes has
been acting oddly.  It prints without errors of any type,
but the output will only show the return address rather
than both the return address and the send-to address.  The
orientation is correct on the feeder, as the return
address appears in the right place.  We've tried different
printers and reinstall the application with no success.  
However, if you open a normal word document and change the
page settings for #10 envelope and envelope feeder as the
source, it will print the send-to address.  Any ideas?