Going through the menu to get to the Nvidia settings shows a driver of 290.10. I appears that your driver is a later one or is it because you have a different card.
I believe 295.40 is still being tested thus it's in the testing
section of the repo.
Quite often when new drivers come out they are first placed in the testing
section so any bugs etc can be traced and reported on enabling the devs, if possible, to iron them out.
One thing to note is that apps/drivers etc that are being tested aren't reported on using the forum, it's done via the testing group using email@example.com
Also of note, the testing group isn't a place to expect fixes
, it's more to notify the devs of any issues that have cropped up whilst testing that particular item, which helps them decide on when or if to release as it as part of the "normal" update process.
The 295.40 update was mainly a security fix release thus no major changes to earlier 295.xx releases.
It seems that the problem lies with the video.
If you think updating to 295.40 may cure your issue you would need to add (bearing in mind the above) the word testing in Synaptic.
Synaptic > Repositories > choose ONE
repo only and in the section(s) box add the word testing so it reads something likemain updates nonfree games kde4 testing
and do a reload.
As mentioned, select only one
repo but not
server as that feeds the mirrors (the exception is having the games repo selected as well)