Plines width not showing solid

The Plines that I am using on my drawing do not appear solid when I change to the required global width, all my system variable are set correctly however the lines are showing 'doubled'. How do I rectify this please ?

Thanks

AutoCAD 2013 Mechanical SP2

64-bit HP Z400, Intel Xeon W3550 3.07GHz

12.0GB RAM, ATI FirePro V4800 (FireGL)

Image may be NSFW.
Clik here to view.Image may be NSFW.
Clik here to view.Image may be NSFW.
Clik here to view.Image may be NSFW.
Clik here to view.Image may be NSFW.
Clik here to view.

Image may be NSFW.
Clik here to view.