After Ubuntu published the latest Kernel Patches for Meltdown and Spectre the Kernel 4.4.0-104/109-generic let Intel Graphics freeze or hang on Compiz with Unity.
Howto fix:
Install the latest Kernel 4.4.0-112-generic
do:
sudo apt-get install linux-image-4.4.0-112-generic sudo apt-get install linux-image-extra-4.4.0-112-generic
reboot
then:
sudo apt-get autoremove --purge -y
This removes older kernels and save Space! Do test the PC for hanging again!!!