While it is true that program outcomes are entirely logical (ignoring faulty hardware), the randomness is generated from the users actions. As an example (I'm not a games programmer, so this example might not actually ever be the case):

Lets say it is a sandbox game like GTA so there isn't any 'levels' persay but a world where objects are required to be loaded in and out of memory in realtime. So as the character moves around, if a new object appears within 300m of them, it will be loaded into memory, and if a 'unique' object (only one instant in 300m) goes out of range, it is unloaded.

Now the adventurous gamer comes along and explores every place in the game, and ends up in an uncommon situation. While every effort has been made to fit all objects in a 300m raidus of the gamer into memory, this one particular place ends up with too many objects. Now to stop the game from crashing, the programmers will have put a fail safe to not load the object into memory if there is no room left, even if it is entirely assumed this will *never* occur. The gamer now explores futher, and because the now 'missing' object is never reloaded, they comes across the place where the object should have been only to find the object not there.

Now this doesn't excuse poor programming as this can theoretically be avoided. Instead of just loading objects as they hit the 300m range then ignoring them, we can perform another check. For this example, let's say that if an object sits within 100m, we recheck that we actually loaded it. If not, we discard the futhest object from the player and load in the closer object. Sounds like it should solve this issue right? We unfortunately this causes us to use extra cpu time and this might be the difference between smooth gameplay, and the game slowing down 'randomly' when we need to perform a large number of checks at once, so because the issue is "never" likely to occur, this check is ignored as the side effect is much greater and more noticable.

Hopefully this gives you a bit of insight into why 'random' bugs can occur.

 The only reason you think that is because you have never programmed. Bugs are random as all hell. They are also absolutely impssobile to fully eliminate. The old rule I was taiught was for every 1 bug you fix, two more are introduced. How code will behave in a real environment is impossible to fully predict. You can definatly have a good idea what will happen, but there will always be some strange set of circumstances that causes a complete melt down for no apparent reason.

Edit: Kat explained it much beter.

thanx guys... I am still under the impression that this is human error on one level or another... sure games become more complex and so do the problems... still Pong never had a bug... Tetris never had one... perfection is possible... sure there are scedules but if quality suffers this much maybe a few more months of production would have been better...

Missing lever?

Beta test much? finish the game before releasing?

it's pretty laughable.

 It absolutely is human error. A certain amount of human error is to be expected though. Also, I would bet money there were some bugs in those games. They are just so hard to reproduce no one really knows about them.

LIES !!! Saying Tetris has a bug is like saying Chess has a bug... perfection doesn´t work that way...

Maybe I´m not thinking abstract enough but for me ether you put something somewhere and its there or you don´t... the end... and I also don´t get this talk about not beeing able to reproduce a mistake... why didn´t they just call me ??? I can reproduce any mistake any amount of times... I could even make some new ones...

As the possibily space grows, the chance of finding certain bugs can become miniscule. For example, let's say that a bug occurs at a ceratin point in the game due to an error in the code for a part of the game that happened 5 hours earlier. Let's say at the point of the error, there were 10 possibilities, of which 1 had the error, and at the point the bug becomes apparent, there were another 10 possibilities, of which only 1 triggers the bug. In this example, the error only occurs 1 in 100 times assuming an entire random selection.

This random selection may not even be the case. Say the first option is usually selected because the character is a fighter, but the second option would usually be selected because a character is a mage. Now this reduces the possibility of this happening because most gamers would not select an option for a fighter then an option for the mage.

Now to make things even worse, lets say that during the 5 hours of gameplay in between, certain other events can cancel out this bug. Now this increases the possibility space even futher.

While Pong and Tetris may be 'bug free' (you can't actually prove the absence of bugs, at least not feasibly for non-trivial programs), these games are extremely simple compared to the game of today and have a much, much, much, much smaller possibility space.

thanx for helping to solve this... I get your point and how complex these things can be... still in this situation the Lever has to be there 100% of the time... there is no cenario in which the Lever should not be there... how can there be a situation in which this occours and how can it be so ramdom ???... thats like a bug where the floor dissapears... it always has to be there... there is no situation where it shouldn´t... anyway don´t bother trying to explain any further... I get how this can happen in theory... just how something so obviously wrong which isn´t an isolated incident can be in a shipped game is bejond me...

You wonder who tested this game.

^^ People payed by the makers of the new Prince of Persia ???