Had this issue myself and found it so annoying I just couldn't read the site at all. However, quite an easy fix for this.
Right click anywhere, and chose "Refresh Every.." a small popout window should appear, saying "Every 0.5 sec, 1 sec, 5 sec" and so on. on the bottom, it probably says something such as "Use sites standard" or similar.
Just click "Never" to prevent the site from refreshing itself. And that should take care of the auto refreshing. At least in Opera, I don't know if Firefox has the same settings, if it is then it's probably in the config file.
Small edit: You might have to do this each time you enter the site in a new window or such, as it doesn't seem like the browser remembers it.