Comma issue in modal pop up

n the login section I have a username, password textbox, submit button and forgot password link button. All are encapsulated in an update panel. On entering invalid login username / password, a lable displays error message as 'Invalid username/passw开发者_JAVA技巧ord'. After that when I click on forgot password, a modal pop up opens which contains username/emailid text boxes. The problem is the text boxes displays comma(,) in the textbox automatically. I tried to clear the textbox value (comma) using javascript on forgot password link button click but i am not able to clear that textbox values.Hope u can better understand now!

I have placed the modal pop up panel outside the update panel and now the comma does not appear except that the flickering effect occurs due to reloading of controls present inside modal pop up.