I have been using Ubuntu some few times on my computer. I installed it some weeks ago alongside windows 7 on a own hard drive. I installed the Nvidia drivers with this guide http://www.ubuntugeek.com/howto-install-nvidia-drivers-manually-on-ubuntu-10-04-lucid-lynx.html and did everything in it. After that everything seemed fine and I can play kerbal space program nicely without any kinds of graphical problems. I'm also using dual-screen (2 screens). But when I do stuff like surfing on internet or playing music. or surfing on web at my 2nd screen and playing kerbal space program on the main screen ubuntu freeze many times. When that happends my mouse can move around but is stuck at the screen it was on when it froze. I can hear sounds from the game like it is still going. I can go back to the terminal screen. Only solution is restarting my computer. But why does this happens? It is really annoying because this is happening allot. I have also use system monitor while playing (even before a freeze) and the RAM is FAR from overloaded and the processor is working at like 10-40% when it is crashing.
Specs: AMD Athlon(tm) II X4 645 Processor 3.10 GHz 12 GB RAM 64 bit system (ubuntu 14.04 LTS 64 Bit) Nvidia Gainward Geforce 550 Ti Graphics card