4
Alright, there are numerous reasons why this could be occuring.
I cant peg it down because the source is way to cluttered.
From a birds eye view it looks like you have various overlapping tables, and a lot of bad code.
use
This and get your page compliant. Ihave found that in most cases this will fix structural issues as well.
I was not able to reproduce the issue you were talking about. If you would post up the contents of your theme.html we could take a closer look and see if we can nail down the actual problem.
I feel that because of the intermittent occurrence that this may actually be related to content from one of the iframes, or content you are pulling from another domain. Have you noticed that it only occurs when certain external content is loaded?