Thank you for the information.
I've read about a kind of similar problem in issue 0004845 and thus tried to run the game (experimental 42.116002) with the built-in intel graphics and not the amd radeon hd 6550m.

> I was able to launch the game and enter a server, but it was unplayable. The graphics were horrible, it was shaking and juddering and I wasn't able to change to 3rd person view.