I've been writing my own Matrix, Vector and Quaternion classes for use in my engine that I'm currently updating to support OpenGL 3.2+.
I've looked over every possible detail, or so I think I have, and cannot fix this error I'm getting. It cuts out the top right portion of the image with the line being rather jagged. It originates from exactly the top left corner, drifts diagonally down to the center of the screen and then changes to a shallower angle towards the right of the screen.
Better explained by the picture below:
Are you drawing a full-screen quad for postprocessing? If you are, I'd suspect that your quad has one vertex in the center of the screen and one slightly offscreen (mapping to x=>1 in the lower right corner