Postback issue with safari

Question

I have a LinkButton, Which call a postback event. When I click on that for some of the clicks that is working fine calling the post back event after that on the same linkbutton click it is calling the page reload event where private keys are getting changed giving me trouble. Actually that link button is Captcha Refresh button were wrote the event for recreating the captcha from Random. The refresh button is working fine with chrome and FireFox. Only the safari browser is calling the page reaload event after some clicks on the same button.

Postback issue with safari (Calls Pagereload but the postback request has been sent)