force reboot linux server

# this command is more powerfull than reboot -f
echo “b” > /proc/sysrq-trigger

How to fix transparent virtualbox window in ubuntu

If the virtual box window is transparent -

change the launcher shortcut command from : "VirtualBox" to :

"env XLIB_SKIP_ARGB_VISUALS=1 VirtualBox"

how to install nvidia driver in ubuntu

envy : http://albertomilone.com/nvidia_scripts1.html

nvidia-settings

(if there is problem saving config then : rm /etc/X11/xorg.conf; nvidia-xconfig)