scripts/pollmanager.inc.php

Line 114 has a block of code that looks like this:

Code
if ($enablestart) {
   $starttime = mktime($hour,$min,0,$month,$day,$year);
} else {
   $starttime = mktime(12,0,0,$month,$day,$year);
} 
$validstart = checkdate($month,$day,$year);  
if (!$validstart) { 
   $html -> not_right("{$ubbt_lang['INVALID_START']}");
}

Change that, to this:

Code
if ($enablestart) {
   $starttime = mktime($hour,$min,0,$month,$day,$year);
   $validstart = checkdate($month,$day,$year);
   if (!$validstart) {
      $html -> not_right("{$ubbt_lang['INVALID_START']}");
   }
} else {
   $starttime = $html->get_date();
}