The problem with all online Steam games:BEX

This problem appeared recently: I can't launch the game(online game just), as it immediately POPs up a window with a BEX problem. I have no idea what I want to do, because I have tried many solutions: checking the cache x5, x2 reinstall, delete cache download x3 full system scan for viruses x6 and many other solutions for this trouble(without of downloads of different software), found on the forums.
Please help to solve this problem.