I know there's a growing movement to ignore IE6 users, but this is just too weird. If you go to my site, mpkb.org, in Internet Explorer 6, you should see that the look changes somewhat randomly when you move from one page to the next and when you refresh your browser. Sometimes it's as intended and uses the design.css stylesheet. Other times you'll see it using the print.css stylesheet for display in the browser. Other times, it won't use any stylesheet and the page looks like a dog's breakfast.
I'm not sure why this is.
Possibly related: on my test site I get the PHP warning, "PHP Warning: Cannot modify header information - headers already sent in Unknown on line 0"
I've tried using a default theme and disabling my plugins, but those errors are consistent.
Paul
p.s. I looked here and this advice didn't help.
http://www.freelists.org/post/dokuwiki/Howto-debug-php-Cannot-modify-header-information-errors