I recently installed TF2 and CS:S on my Ubuntu and it was showing nothing but a black screen (I could still hear the sounds) and after searching a bit I found out it may be my OpenGL version.
glxinfo|grep "OpenGL version" in the terminal it shows
OpenGL version string: 2.1 Mesa 9.0
The thing is I don't know how to update it, I searched for additional drivers in software resources and none were listed (which isn't normal in my opinion) and after checking for drivers on my laptop's website I couldn't install anything because they don't have linux support.
My laptop is: Acer Aspire 5732z Graphics Card: Intel GMA 4500M