var bFound = false;
for(i=0; i < document.forms[0].length; i++)
{
  if (document.forms[0][i].type != "hidden")
  {
    if (document.forms[0][i].disabled != true)
    {
        document.forms[0][i].focus();
        var bFound = true;
    }
  }
  if (bFound == true)
    break;
}