Thanks, unfortunately I have still not been able to reproduce the issue. I also tried testing your script under Windows XP, with different versions of mIRC, and they all returned "1 -- 1 -- 0".
I also installed WinRAR, as well as other archivers, with no difference to the result. It looks the type of archiver is not relevant in this case - the $com() call seems to be calling the Windows built-in zip support.
It may be that there is an issue with your Windows built-in zip configuration that is causing the issue. Other than that, I am not sure what else to suggest without being able to reproduce it myself.
