3rd Column moving?

hey guys, just finished my site, uploaded it. worked fine offline, check it out:

http://aboutchris.co.uk/CP/index.htm

Heres a picture of what it's doing on my screen, It works fine for some people

http://img80.imageshack.us/my.php?image=messpr6.jpg

CSS:
http://aboutchris.co.uk/CP/_css/main.css

HTML (View Source):
http://aboutchris.co.uk/CP/index.htm

Thanks guys, I really can't get my head around what's going wrong?!

floating/width issue

http://bonrouge.com/3c-hf-fluid-lc.php
http://www.quirksmode.org/css/clearing.html

play around with the width. the container width should be greater than all the columns width

Ive double checked. Fixed it now on mine, its an issue when you scroll out? When you scroll in far enough it likes its fine?

Ive double checked. Fixed it now on mine, its an issue when you scroll out? When you scroll in far enough it likes its fine?
You what?
Your page works fine when my browser window is less than the required width: it just sticks a scrollbar in. When it's more, the content is centered. It all looks like it should, with no breaking columns or silly things like that. Yay =)