Things that stop NPCs

[Yen]

Zodiac's inventory has a major bug.
It randomly stops. By stopping, I mean it doesn't carry out any functions or catch any events.
I have no idea what causes it. The only thing I can think of that stops an NPC like this is when a script exceeds the loop limit. The console log doesn't give a loop limit exceeded error.

I can't fully debug the problem, because I can't make the bug happen to myself. However, a majority of Zodiac has it. These bugged players all seem to have the Stealth skill, but I also have it and I'm not experiencing the bug.

PHP Code:

//Skill: Stealth
function onActionServerside() {
  if (params[0] == "cast") {
    player.TakeMP(25,"skill");
  }
}
//#CLIENTSIDE
function onCreated() {
  join("systemfunctions");
  join("mudfunctions");
  this.spelltime = .4;
  this.spellpower = 0;
  this.manacost = 25;
  this.element = "Dark";
  this.description = "Makes you invisible to|others for a while.";
  this.castani = "carrystill";
}

function onCast() {
  if (clientr.stat.mp < this.manacost) return;
  setani("carrystill",NULL);
  this.ftime = .5;
  if (clientr.cmp.shadowblanket > 0) this.ftime -= clientr.cmp.shadowblanket * .1;
  freezeplayer(this.ftime);
  findweapon("+System").AddBuff(/*Params clipped*/);
  sleep(this.ftime);
  setani("y-animation-hidden",NULL);
  player.chat = " ";
  if (clientr.element == "Dark") {
    temp.stealthtime = clientr.levels.Thief * 1.5;
  }
  else if (clientr.element == "Light") {
    temp.stealthtime = clientr.levels.Thief * .5;
  }
  else {
    temp.stealthtime = clientr.levels.Thief * 1.5;
  }
  temp.modz = clientr.mods;
  while (temp.modz.index("stealthup") >= 0) {
    temp.stealthtime += temp.modz[temp.modz.index("stealthup")+1];
    temp.modz.delete(temp.modz.index("stealthup")+1);
    temp.modz.delete(temp.modz.index("stealthup"));
  }
  findweapon("+System").AddBuff(/*Params clipped*/);
  triggerserver("gui",name,"cast");
}

public function CanCast() {
  if (HasBuff("invisible")) return false;
  return true;
} 


PHP Code:

//System: Stealth-related functions
public function AddBuff(/*Params clipped*/) {
  switch (type) {
    case "invisible":
      this.invisible.duration = time;
      replaceani("walk","y-animation-hidden");
      replaceani("idle","y-animation-hidden");
      player.attr[3] = "";
      RemoveEffects();
      break;
  }
}

function RemoveEffects() {
  for (b = 7; b < 28; b++) {
    player.attr[b] = "";
  }
}

function onTimeout() {
  for (/*Buff stuff*/) {
    if (a[3] == "invisible") {
      this.invisible.duration -= .05;
      if (player.ani != "y-animation-hidden") {
        this.invisible.duration = 0;
      }
      if (this.invisible.duration <= 0) {
        RemoveBuff("invisible");
      }
    }
  }
}

public function RemoveBuff(/*Params clipped*/) {
  this.(@type).duration = 0;

  switch (type) {
    case "invisible":
      replaceani("walk",client.gani.walk);
      replaceani("idle",client.gani.idle);
      replaceani("sit","sit");
      this.updateicon = 0;
      if (player.ani == "y-animation-hidden") setani(client.gani.idle,player.attr[2]);
      UpdateBuffs();
    break;
  }
}

function UpdateBuffs() {
  for (b = 7; b < 28; b++) {
    player.attr[b] = "";
  }
  for (/*Buff stuff*/) {
    player.attr[7+a] = /*Buff effect var clipped*/;
  }
} 


Clipped out not-so-important parts that people-shouldn't-be-seeing.