framelike behaviour in Mozillabased Browsers

Hello all,

I am working on a page layout which is using fixed CSS Block Elements
for a Framelike appearance. Unfortunately, as I view my (dirty) work
in Firefox 0.8 on Windows XP SP1 I always get an unwanted horizontal
scrollbar in addition to the vertical scrollbar.

Could maybe someone glance through the Code on the Test-Webpages I
created?

This is how it looks like:
http://tomasio.laudatio.com/temp/Cb_meyerframes.html

This is how I'd like it to appear in Mozilla and (if possible at all)
in IE:
http://tomasio.laudatio.com/temp/Frametest_HTML.html

Any help would be highly appreciated.

Kind regards,
tomasio