If this happens "sometimes", it sounds like "bit crowding"
(my term
) on the page layout. In other words, you're
trying to use all available space on the printable page,
and the bits that represent the bottom cell borders
are "falling off the edge." You might try a couple of
things:
1. Open the bottom page margin slightly (0.1 inch) and
see if that helps. Don't open it more than a row's
height, or the next row will slip in to that page, and you
might have the same problem again.
2. It also sounds like you might have set some Page View
options, perhaps to control how much of a sheet prints out
on each page, for neatness or for separating distinct
parts of the sheet in the printout. If that's true, is it
also true that shorter pages print okay but full pages
sometimes don't print the bottom edge? If that's also
true, then you are pushing the printing capability at this
last row of bits on the page too hard. If this is all
true and you have the option to change it, try sneaking
the lower boundary of the "full" pages up a row.
3. Print preview is notorious for not showing some (even
many) horizontal lines on a page. I think this has to do
with the slight mismatches between the page layout and how
the bit map image of that layout plays out on a screen,
especially if the screen res is not VERY high. However,
thick lines should show up, regardless.
Sorry - these are only thoughts - I can't point to a bug.
I really think you're up against a page layout problem.
Maybe someone else has a better technical answer.
