Hey, I've just found that http://www.glowhost.com/forums/memberlist.php is broken.
This is the way it looks in FireFox 2.0 http://www.zoffix.com/new/del/glow.png
And this is IE 6 http://www.zoffix.com/new/del/glow1.png
Basically, your table overflows, thus causing ugly effects especially with the background.
I just noticed that I see the overflow right in the window I am typing right now =)
I'm using 1158xsomthing resolutiong
You may look into CSS Overflow property ( http://w3.org/TR/CSS21/visufx.html#propdef-overflow )
Cheers