I sent a mail to Julien and he said for i install everything new and update my graphic card driver (this is like the standard answer you always get )
I reinstalled C2 & my drivers and at first it seems that everything works fine, but now it starts again that the C2 enviroment doesn't respond quite often when pressing a button in the event sheet or just trying to open the file menu.
The editor hangs for some seconds before responding to my input. It really is no fun to work at all with C2 at the moment.
I have a feeling it might be a steam issue, but also if, the developers should go after this, maybe make contact with the steam staff to figure it out - maybe it is just something new in the steam api that should be changed.
Also because i bought on steam i paid a (for me not so small) amount of money, for that i could aspect that the software works. (special because i really like C2 more than any other game engine).