hi,
i have the same problem with ninjatrader 8 and the update - i work 5 min with only 2 charts, when i open the third chart all is freezing.
i was in contact with ninjasupport full 3!!! month , they found the issue and now in the next update they will...

http://www.invest74.ru/index.php?topic=9008.msg27213#msg27213