A Task Normalcy Fatality Loop, or TNFL is any type of infinite loop occurring within a program in which the operating system loses the ability to properly control the activities of the program indefinitely.

In terms of most PC games, it means that the game has entered an infinite loop in which until the conditions are met, the game has locked the controls that would allow the player to close the game, thereby requiring the player to use the Windows Task Manager as a means to exit the problematic game. In extreme cases of physical lock down of hardware such as the hard drive, it may even be necessary to turn off the computer completely in order to get around the problem. Some problems, however, may be fixable with the Simsky Antidisasta Remote.

Frequency of occurrence

TNFL's could theoretically occur in almost any software application, but games are particularly susceptible. This is often understood to be the case with games that have very complex cheat consoles. Perhaps the most well-documented game with such design flaws that has been noted by Dozerfleet Productions is The Sims 2.

Occurrence Within The Sims 2 and Expansions

The most common TNFL-inducing problems within The Sims 2 and its expansions are referred to as Infinite Loop Syndromes, or "ILS." The two most common ILS's in this game franchise are BI-SWILS and CT-BILS, as documented below.

Note: The Sims 3 uses a very different system for aging Sims, combined with a "universal evolution" throughout neighborhoods, to avoid the time warp paradoxes that existed in earlier versions of the game such as Sims 2. In the process, many of the harmful logic problems documented below have been eliminated in Sims 3.



CT-BILS is an acronym for "Corrupt Twin Birth Infinite Loop Syndrome."

  • It occurs in the game usually as a result of a failure to execute the birth animation script a second time when a woman is giving birth to twins.
  • The second twin will be born, but the game will lock out the neighborhood menu and the exit menu until the animation is fully executed the second time. Due to the paradox of CT-BILS, the menus will never unlock.
  • Misuse of Jase's InTeenimator hack has been known to aggravate the condition, which may be brought on by having multiple NPC's on a lot when a woman is giving birth.
  • CT-BILS can also be brought on by having the woman give birth to twins on a lot that normally does not allow pregnant women on it.


  • The best advice is to avoid using hacks, since these void the EA/Maxis warranty anyway.
  • However, if one is afflicted with at TNFL anyway, then the only real advice is to use the Task Manager to close the game.
  • You should try having the woman give birth again. This time, however, you should make sure to deactivate any known problematic cheats before you proceed.


On a Windows PC:

  1. Once inflicted with CT-BILS, you must type Ctrl+Alt+Delete on your keyboard to bring up the Windows Task Manager.
  2. From there, you must select the Applications Tab and then select the application from the menu.
  3. Next, you must hit the End Task button. A pop-up will announce that the game is non-responsive.
  4. Click on the End Now button to force-quit the application.

On a Mac:

If it is possible to play within a window, then use the window's menu and select the Force-Quit Application option.

On Linux:


A more common and much more dangerous type of problem that the game can encounter is BI-SWILS, or Boddler-Induced Social Worker Infinite Loop Syndrome.

Main article: BI-SWILS


Trapping any infant, toddler, or child inside of some barrier so as to be inaccessible will result in a condition known as CHild-In-Trap-Induced Social Worker Infinite Loop Syndrome, or CHITI-SWILS. This is not always a true infinite loop, as there is a possibility of the young one dying from neglect. This will cause a frustrated Social Worker. If she realizes the child is dead, she may then agree to leave, thereby ending the loop.


If the social worker decides to stay on the lot forever in search of a dead child, then you will have DEad CHild-Induced Social Worker Infinite Loop Syndrome, or DECHI-SWILS. The problem that makes Social Workers such buggy NPCs is that they simply will not leave most of the time until they have accomplished the task for which they were sent.

Most other NPCs, upon failing to find what they want, usually leave the lot empty-handed. The easiest solution to this problem is to NOT trap children in any location where a Social Worker would not be able to get them. Also, don't neglect the children. Avoiding doing so ensures that the Social Worker will never arrive.

The reason why CHITI-SWILS and DECHI-SWILS are possible in-game is because the game tries to have the Social Worker remove Babies, Toddlers, and Children from the lots before they die. In other words, the game sends the Social Worker after a starving Baby since Babies aren't normally allowed to die. The same goes for the game's insistence that Babies and Toddlers cannot burn to death (but Children can.) This is done primarily so that the game can continue to be politically correct.


VEhicle Return Failure Infinite Loop Syndrome, or VERFILS, is a potential bug that can happen when a Nightlife vehicle tries to return to a lot or leave a lot unsuccessfully, and does not reset. This is extremely rare. Just like Social Worker Infinite Loop Syndromes, this one locks up the game so that the player cannot exit. Using Windows Task Manager is the solution in this rare but inconvenient occurrence.


Corrupt Lot Loading Failure Infinite Loop Syndrome, or CLL-FILS, is the result of a lot file that loads improperly or cannot load at all. This is the most commonly reported of the infinite loop syndromes. There is no one single cause for CLL-FILS, but the result is the same regardless the cause. The game becomes locked and requires Task Manager intervention due to a faulty object making a lot unplayable.


This is not an infinite loop, but is still a TNFL. The acronym stands for MUsic Role SWItch Syndrome. If switching game modes too quickly, the music module might get confused and play on the wrong mode. To fix this, simply save the game and exit. Upon restarting the game, the problem will correct itself.

Other problems

The Task Normalcy Fatality Loop isn't the only problem that can happen in a game environment. Another problem that can occur is the Task Normalcy Menace, or TNM.

This is not an infinite loop, but it can, like an infinite loop, wreak havoc on the interoperability of the OS and the game. In The Sims 2, the most common example of a TNM is the disabled Weather feature. This causes incredible strain on the Task Manager, especially in regards to Virtual Memory depletion. To fix this problem, especially given the Modding Community's discovery of how to unlock weather, Maxis decided in 2006 to create the Expansion Pack Seasons specifically to correct these problems.

See also

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