Getting funky in MSIE 5 and 6

I've got a page with a little primitive drop shadow:
<http://www.crispen.org/web_building/simple.html> and I've noticed in
MSIE 5 that the header sticks out at the top sometimes (but when you page
down and back up, this goes away).

MSIE 6 does sorta the opposite: it looks fine at first, but if you page
down and then sorta sneak back up, the color doesn't display on the whole
top. If you page up quickly, it displays fine.

The style sheet is <http://www.crispen.org/web_building/simple.css>, to
save you a lookup. Is there a way to work around the funkiness?
--
Bob Crispen
bob.crispen (AT) boeing (DOT) com

There's plenty of room for all of God's creatures.
Right next to the mashed potatoes.