I'd almost assume the script you are using is being banned for a purpose.
Anyways,
Could you paste the exact kill reason? You arnt giving us much to work on, from what I see is one of three things.
A) Trojan on/in your client.
B) This script that you dont wish to mention may be a IRC-Orks or Bottler Bot script which is forbidden on any decent network.
C) Your host simply may be banned, your fault or not, may have been somone on your ip/host in the past.
** Had another thought, I'm a server-co-admin on a seperate network and we do ASK for ALL users to use updated mirc versions, since most all previous versions have exploits in them. You can easily scan for what version you are running upon connection to the server and deny acess if you're caught using a outdated version.
To fix this just simply download the latest mirc off
www.mirc.com, install it to some arbitrary directory, copy out the mirc32.exe and place into your scripts. Then you can presume to delete the plain jame mirc you just installed since its of no use.