vertical placement oddity

[Jeffrey J. Gray]

Hi,

I've uncovered some odd behavior that I can't seem to get rid of or find
in documentation or FAQs...  When I use \flushbottom on my document,
line spacing expands to fill up pages, but the subsection headings do
not move along with the rest of the text.  Therefore, the section
headings end up overwriting text in the previous section, and a large
gap is then left between the sections.  (These extreme behavior is only
on a few pages with bad page breaks, but looking closely at other pages
I can see that headings are misplaced vertically)

Any idea what could cause such behavior?  I'm writing a thesis with a
custom package, but the package uses the standard \@startsection to
define the section headings, with appropriate rubber lengths, and I
can't find any other modifications that would affect section headings.
All the other packages I'm using are standard-distribution packages
that, to my knowledge, shouldn't have anything to do with section
headings. (amsmath,latexsym,graphicx,psfrag,rotating,overcite)  I can't
seem to figure out

Thank you for any help you can provide,

Jeff Gray