emacs21: annoying black side stripes

["tom lightbody" <swan36doe@gmail.com>]

hello from New Zealand:

emacs21: debian sarge: xfree86-4: fvwm2: thinkpad 600e/t22

to either side of the main editing window, 2 vertical black
stripes just inside the border.  They are not scrollbars; neither
inside border nor outside border adjustment makes them go away.

with emacs20 (identical .emacs) they do not occur.  But using
emacs20 from potato, causes dependency problems with sarge.

how to rid myself of these 2 black stripes?

thanks
tom