Hi Ashley, and gb2world, thanks for your help. I have installed Firebug, I don't know how I've managed for the past few years without it- it's wonderful!
The site I am working on is at:
http://www.mrdtrading.co.uk/store/home.php?shopkey=meachin
I only started looking at it two days ago, got stuck on this problem and have spent the past few hours properly exploring the site using Firebug.
I've floated #header .line2 right, instead of using Qualiteam's
margin-left:250px
or whatever it used to say.
If I float #header .line 2 left, it works fine!