Seems related to issues 13317  and 15952.

Tried printing labels on Avery Letter 5366. The labels generate correctly and
look right on the screen. When printed on an HP LaserJet 1100 they seem shifted
~0.25" left and ~0.15" up, so they are not aligned on the page.
This is true for 1.1rc2 on Windows 98SE, and 1.1rc3 on Windows 2000. Haven't
tried other versions or other OSes.

I tried printing to a Samsung ML-1650 from the Windows 2000 computer and the
labels were shifted on that printer as well, though perhaps a little less so.

By creating a custom label with different offsets I was able to get it to print.
 For comparison, the values that worked were: H.Pitch=4.00", V.Pitch=0.66",
Width=3.35", Height=0.66", Left Margin=0.75", Top Margin=0.61"

It may be related that when these are generated the page size (under the menus
at Format->Page) is switched to User [8.55" x 10.51"].  The page will still
print normally, but I'm wondering why the page size is set to something
other than Letter when generating these "Avery Letter Sized" labels.  I
tried setting the page size to Letter to see if that would fix the margin
problem, but it doesn't.  Instead it just breaks the whole label formating
by acting like they can't fit on the page and having 2 pages, each with 1
column of labels, instead of the correct 2 columns of labels.

I love the program other than trying to get these labels working!