This has been reported in the following Debian bug report. I've checked -
the behaviour does appear in galeon but not mozilla.

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=215746

Starting with galeon in a given window position, following a symlink
pointing to a local link (e.g. <a href="#foo">...</a>) and then going
back using the "back" button should return to the original window
position.

This is true, _but_ at the first click on the page (not on a link), the
window position moves to a somewhat random position apprositimatively
half a way from the original position and the link target previously
followed.

I hope it's clear. If not try the following:

1) open the attached a.html file
  [ you're now at the beginning of the window, seeing "foo" as the first
  row ]
2) click on the "foo" link
  [ you're now at number "69" ]
3) click on the "back" button
  [ you're again at the beginning of the window ]
4) click anyware on the html document (e.g. on the number "10")
  [ you're now seeing number "40" ]

This is very painful when you're reading huge html documents like the
W3C specifications ... you lost you're reading point quite often.

This bug seems not to apply to mozilla.