Hi tanchunsian,
Sorry about the late reply! If you also have Little Math installed in the laptop and computer where you have LR, are you also having similar crash problems when you use Little Math?
In the meantime, kindly send us a diagnostic report so we can troubleshoot immediately. You may find instructions on how to create a report here:
http://support.brillkids.com/index.php/article/ls-how-to-create-diagnostic-report