(In reply to ruben from comment #0)
> Created attachment 119677 [details]
> dmesg output from boot onwards
> 
> The desktop freezes consistently after a few minutes using the nouveau
> driver.
> 
> Only the mouse can still be used. The system is still fully  operational and
> reachable via ssh.

I have the same behaviour on a Latitude e6420 with NVIDIA Corporation GF119M
[NVS 4200M] GPU.

> Have you noticed anything that may cause the freeze, like starting a browser, 
> running some OpenGL application, or even some fancy compositor animation?

No. The crashes happen at random intervals. Most of the time there isn't any
intensive application opened when it happens. Regarding the compositor, in my
case, the freeze happens even if there isn't any actively used.
The software versions I'm using are:
xf86-video-nouveau 1.0.11+31+g1ff13a9
mesa 11.0.6
xorg-server 1.18.0
plasma-workspace 5.4.95 (happened with a stable version as well 5.4.3)

If you connect via ssh, you can see on the dmesg can be seen the following
error:
> nouveau E[   PFIFO][0000:01:00.0] INTR 0x00800000
most of the time preceaded by:
> nouveau W[   PFIFO][0000:01:00.0] INTR 0x01000000: 0x00000005

Also the full trace of this failure can be observed on the Xorg log.
I've attached all logs on the raported 'Bug 71659'.