I am writing a dynamic website that uses PHP/Mysql to load content, yadda yadda. That part is moot.
When I'm viewing my site in firefox, if I scroll halfway down and click refresh, it jumps to the top of the page. This doesn't happen in IE on the same page. Is this some kind of problem with dynamic navigation bars influenced by PHP?
An example is on this site (not mine) scroll down some and click refresh in FireFox:
What, in general, causes this to happen? How to large sites like HP.com that are heavy dynamic content stop this from happening?