Lot of users told me about log-out and token issues with the purepro theme.
Text Formatted Code
$loggedInUser = !COM_isAnonUser();
if( $loggedInUser) {
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Expires: Sat, 26 Jul 1997 05:00:00 GMT"); // Date in the past
}
Everything seems to be ok now. No more log-out or token issues.