[Nouveau] Screen freeze

[abcd]

Hi again,

I have a strange problem here and I don't know how to debug this:

I have mesa installed on Debian jessie with a GTX 660Ti with UEFI VBIOS,
installation from jessie-backports via apt-get and done a kernel update.
All glx commands like glxinfo, glxgears, glxdemo, etc. are working. When
I try to run some applications, it's the hardware accelerated
ones, like some games or Opera Internet Browser, my screen freezes,
I can only move the mouse and shutdown the system on power switch.

glxinfo | grep 'renderer string' gives:
OpenGL renderer string: Gallium 0.4 on NVE4

How can I find out the problem, now that I always have to shutdown the
computer?

Thanks in advance!
Cheers