Controlling Tab between input fields

This is kinda odd, whenever I hit tab… The writing cursor skips to a seemingly random input field, instead of simply going to the right until the end, then the next row. The input fields are kinda close, but everything is symmetrical. Any ideas about how to control the behavior of input forms?

See what I’m talking about:
http://www.designmichael.com/flashyrss/usercp.php

Just hold down tab… It’s rather hilariously random… lol! In HTML forms, tabs simply go left to right, then next row.