UPDATE: As I said earlier I know nothing about scripts but I do understand a little bit about how ports work with them. I have just downloaded two programs - CurrPorts and PFPortChecker.
I know mIRC uses port 113 for DDC chat (yes?). I have it set in my router for TCP (even though an Op set it up this way, I have tried it set to Both as well).
When I have the script running, in CurrPorts it doesn't show mIRC using port 113. It does show port 59 and another port up in the 50000s and if I initiate a DCC Chat it also shows port 1024.
PFPortChecker says port 113 is open which it doesn't do for the other ports mIRC is using - it says 'could not check because another application has that port locked'. This would be mIRC right? So shouldn't port 113 also be locked?
I don't know if any of that is relevant and I may be completely off base here but I figure any little bit of info helps.