black screen/game not loading

[NightTwix]

since a few days i have this very annoying problem.

i start the game this way:
cd <installpath>/regnum
./rolauncher

worked fine ever since i played.
just in the past days the game doesnt start any more.

the launcher loades fine. i can login and press play.
then the game itself starts, but nothing more happens.
The game window appears but remains black. CPU time jumps to 100% (on one core)
but the usual "console" messages dont appear.

all i can do is a "killall -9 game".

Deleting the live-folder doesnt help.

I have a 2nd PC. So what i do each day is to copy the whole regnum folder over to my main PC. Then i can play again.
On the 2nd PC i dont have these problems, so it could be related to my machine.
on the other hand i dont really play much on the 2nd one.

I know there could be many sources of that problem, but i really dont know where to start looking or how to debug this.
I tried to strace the startup but the rolauncher spawns the game process so it detaches first and doesnt show anything.

any hints welcome