When I use 'View Using GPU' and resize an element, my Width and Height box (near my cursor) turns to a dark gray box. Also, the bounding box has strange line on top and bottom.
Apart from an inadequate card, the issue can be caused by lack of driver updating, lack of proper recognition of the card by the computer, and whatnot (including rifts in the space time, moon, weather, and the fact that Illy (job description Adobe Illustrator) sometimes moves in mysterious ways).