After making a part of a sketch, I draw a line and it is invisible. I tried to draw other figures (circles etc) and made sure it was not for construction, however it is still invisible. The lines are there, I see the endpoints, but the line it self is not visible, even if I click exit sketch. Ive only experienced this on one computer. Could it be due to video card problems? Further info: I am using a 1um grid and drawing sketches about 100um x 100um. Is resolution an issue? Its a strange problem, any help would be appreciated!