Problems after installing Skype 4.3
Open a terminal window and try to start Skype with this command (copy and paste):
LD_PRELOAD=/usr/lib/i386-linux-gnu/mesa/libGL.so.1 skype
If that's successful, I suggest that you check out this answer to get a persistent solution.
This solution worked for me on Ubuntu 16.04
sudo ln -st /usr/lib/i386-linux-gnu mesa/libGL.so.1
Make sure you have libgl1-mesa-glx installed.