I used to get this, I reinstalled the game after the game couldn't launch and I got that, after that I reverted back to windows 7. I'm on 8.1 now and it's perfect.
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I'm getting it too, on windows 8.0. Apparently the cause is, if you open steam, set it to launch to the library screen and STAY THERE. If you open the store even once, and go back to library, the store has a memory leak that causes steam to crash eventually, and TF2 is dependent on steam to run.