Rectangle drawn has a black triangular face and is attached to the origin

Just starting to use Sketchup free for the first time and found when I drew a flat rectangle that the face was just a black triangle on half of the rectangle. Also when I drew the rectangle not on the origin the triangle linked back to the origin. Could you possible advise?
Also the axis are shown in black and not the red green and blue colours. Can this be altered in this version?
Many Thanks

Noticeable that your profile says you don’t know what graphics card you have. Knowing is crucial to Sketchup so I suggest you find out and report.