mIRC without script: doesnt crash
mIRC with script: crash
Since it doesnt happen when you dont use that script, that says the script is at fault in some way. You need to contact whoever wrote it.
Re the exploits, see
http://www.irchelp.org/irchelp/mirc/exploit.htmlYou have seen for yourself that the one that 6.12 was released to correct doesnt crash 6.12
re ZoneAlarm, if you are going to open ports, then you of course effect overall security. Thats why its important to be very careful who you accept files from. You can limit a range of ports, you dont have to open every port from the default range of 1024-5000, just be sure to put the ports you allow in mIRC's options.