How to set window size in .emacs and have that size respected?

[WalterGR]

In my .emacs ("22.2.1 of 2008-09-05 on vernadsky, modified by Ubuntu")
I set the window size (after changing the default font size):

(set-frame-height (selected-frame) 71)
(set-frame-width (selected-frame) 100)

The width is respected, but the height is not.  During startup, it
first grows the height to 70.  (Hypothesis: 71 is a few pixels too
tall to fit vertically in the screen, so Emacs drops it down to 70.)
Some initialization text flashes at the bottom of the screen.  Then
the height is reduced to 67.

In fact, for any size <71, Emacs will always reduce it by 3.  e.g.
(set-frame-height (selected-frame) 60) will end up with the height
being 57.

How do I get Emacs to respect my chosen window height?

Thanks,

Walter