Not necessarily. You would've had to reinstall the scripts as well. It is unlikely that a missing script is the cause of your problems, as most scripts don't have the level of complexity required for what you're describing.
Unfortunately, based on what you've told me, I can't think of why this has happened, as I (and I'm quite sure several other people) have installed, uninstalled and re-installed mIRC with no problems regarding other usages.
I'm sorry to say that I'm at a loss for ideas at this point. Hopefully someone else will have a suggestion.
