Code:
alias mm {
  var %a = 1, %b = $nick($chan,0)
  while %a <= %b {
    var %addr = $nick($chan,%a)
    %addr = $address(%addr,5)
    if (%addr !isignore) && (%addr !isprotect) {
      .timer 1 %a msg $!nick($chan,%a) $1-
    }
    dec %a
  }
}


Try this.. I have removed the usage of $nvnick as it's no longer supported via the help file, also, due to the noted/corrected bug regarding the usage of parentheses with the if statement, you may wish to ensure that you are running the latest version of mIRC.