how to handle web page views when a postback happens?

Question

say a webpage(say name is: first.aspx) has a simple command button, on click of which a label shows up. i load first.aspx and click that button. as known to everybody this button click event requires postback to the server. now after clicking some other button on the same page it takes me to another page(say second.aspx). now if a user clicks on the browser's "back" button on second.aspx, first.aspx is shown with the label still visible and doesnot load with the default view of the page(as it is seen for the first time)...on clicking back once again it will give the original view..how to handle this problem? i mean to stop the system showing different states of the page that it was gone thru'..

also is there any way to disable the browser's navigation (back/forward) button?

looking for resolutions..