NVIDIA or ATi graphics card not setup by default
From Granular Linux Documentation
Problem
Granular may not, by default, be setup to use the official NVIDIA or ATi drivers for the corresponding cards, and rather resort to using the NVIDIA and ATi drivers bundled with Xorg.
Solution
In this case you'll have to manually configure Granular to use these drivers by using either of NVIDIA Settings tool or ATi Catalyst Control Center.
Find NVIDIA Settings in Menu > System > Configuration > Hardware > NVIDIA Settings.
Find ATi Catalyst Control Center in Menu > System > Configuration > Hardware > ATi Catalyst Control Center.