I know this is a vague question, but I have a production website that I cannot easily publish here...

What kinds of things would cause a quick right-left jog of a page when navigating to it?!

I have been using Paul O's 3-Column, Fixed-Width, Fluid Center, Full-Height Column with Sticky Footer with great success on every page on my website.

It seems that when I go from "checkout.php" to "contact_us.php", that the "contact_us.php" page is getting funky?!

If I checkout --> contact_us --> checkout --> contact_us --> and so on, it does usually keep doing it, but may eventually stop.

As I watch the page-jog, the Header from each page is not moving, so it is like then entire <body> is freaking out versus there being some subtle difference in the pages which basically use the same template...

It is usually re-creatable, but not always.

I'm using FireFox 3.6.13 on a Mac.

The only thing I can think of is that switching from HTTPS to HTTP is having some undesired effect?!

I'd like to share a URL, but that is not possible, so I'm hoping that I've given enough to maybe describe something that has happened to others?!