hi! in my website when session gets timed out nd after that we click on any button or perform action it gives random error as input string not in correct format..

how do i resolve problem??

i've 500 pages in whole website...and 20 master pages...so can't check for session on each page...

i wrote code in global.asax application_error method...tht if error occur and session is null than redirect to default page..it worked....but when page is in frame..it does not refresh the whole pahe..only frame redirects the page...so the panel of master page remains same..