Beginning v7.55, $zip is the name of a built-in identifier, and it doesn't like the syntax you're using, which appears to be related to an alias you've not pasted.
https://en.wikichip.org/wiki/mirc/identifiers/$zip
If you want that line to run an alias instead of the built-in identifier, change that line to contain $/zip or $.zip instead of $zip. If that doesn't help, you're asking about a problem with an alias you've not pasted.
