Ajax Collapsible Panel Active panel problem,,,,

Question

Hi,
I Have an ajax collapsible panel with 9 panels......

my requirement is when the page is loaded first panel should be active ....

for that i use below code....
function pageLoad(sender, args) {


       
       
       $find('CollapsiblePanelExtender1')._doOpen(); 
    }

in one of my panel Radio Buttons are there..so when radiobutton checked changed event id firing in 4th panel again the page is loading and control transfers to the first panel,,,
how can i prevent this...