An Search Engine Watch Forum thread asks Is using DIV positioning for SEO, spam? Basically, CSS positioning allows you to clean up your code so that the positioning of the code itself within the ...

SEOs have been using CSS positioning for years and years as a way to get the more important content positioned in the source code above the more boiler plate content, such as headers, navigation and ...

Just a guess, but have you tried supplying widths for the divs? Consider IEs box model as well, making sure the Parent width is large enough to contain the Child width and the padding/margins.