Idk if this is the right place but its off topic and about gaming but its still support... anyway..

Yes i have tried steam support but they don't answer

When i start a game on steam it starts to validate the files every single time and then when the game is just about to get to the menu it crashes and i dont get WHY?! in the steam log it says that ''a Pool is missing''? im like wtf!? So can anyone help me? It would be awesome! Btw im on a mac. Here is the steam.log: steam.log.zip

Ask if you want to know something i will answer as good as i can.

I had a similar problem with Portal 2. (although this was on PC...)

I know it's pretty standard advice, but you could try verifying the games' cache files and/or defragging them. That's what I did to fix Portal 2. And I mean, doing that from the game's properties window, not booting up the game and letting it do that. Also a note on verifying cache files: It'll often look like it's frozen when it gets to around 100%, but it's actually downloading files it needs or fixing stuff so just leave it as it is.

If the worst comes to the worst, you may have to redownload and reinstall Steam. If it gets even worse than that, the last resort would be to redownload all of your games

get a pc?

try deleting everything in your \steam\ folder beside the steamapps folder (which stores all the games)
when you re-launch steam it will have to update and recreate all the missing files.

when the client has re-updated and everything is ready, try launching a game (any game) and let us know if it works.

also a more reasonable thing to do if the above doesn't work would create a Valve Support ticket to contact them with all the information etc, as they are more suited to help you.
edit: steam support takes a while, just bump your ticket with a new post "Hey it's been a while.. any solutions" etc and someone will get to it.

nothing works i have even deleted the whole steam file and reinstalled steam and 1 game but still the same problem . I tried what u said to Echo but it doesn't work Shitty steam its like it doesn't download all the files cus when i start css that picture whit the guy whit a red thingy in his head dont come up i just go straight to the menu tough there is no meny..... Just the spinning wheel of death

But thx for the advices anyway guys

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OMG YES!!
I got it to work i started css from the application folder in the library !!!! but that didn't work before so i guess you help me TY Echo and 4zb41