System Information:
Windows 7 64bit (SP 1) - NVIDIA GeForce GTX 560
Blender Version
Broken: 2.73 release candidate 273fa0a with NVIDIA GeForce GTX 560
Worked: 2.73 release candidate 273fa0a with INTEL HD Graphics 4000
Short description of error
Grease Pencil fill areas look divided by multiples ray lines
I've tested on two computers and only looks weird on the one that use NVIDIA GeForce GTX 560
Exact steps for others to reproduce the error
Draw with grease pencil and set color fill to 1.0 with a light color to better see the problem