Unresponsive security alert for webstart applications in 8u201 on IE

In the first time of a webstart application being launched by deployment
toolkit, a security warning is prompted to allow running it in all
permissions. This warning is completely frozen and No button can be clicked.
If we kill the child process of IE and the page is relaunched in resumed IE,
the warning becomes operative again. If we turn on IE developer tool (F12),
the warning also becomes operative.