I have a dynamic combo box and a static Ext combo box and i just noticed something this morning.
When you click on the dynamic combo box and open up the options it has the first one selected but if you don't select an option and just click off the control and then open it again it has the second one selected not the first. It does this till it gets to the end.
here is my test page.
Series is the dynamic one and Status is just a transformed select box. It does this in both FF2 and IE7