I have no idea what causes this bug, but I do have a screenshot.

http://www.princeton.edu/~mplough/tmp/blender_bad.jpg
On launch, the checkerboard happens; after pressing some buttons, the dotted lines (scaling) and menu buttons are left over.

System is a 2x 2 GHz Xeon Mac Pro, with an Nvidia 7300 GT video card.

It looks like a buffer swap is never happening; the only drawing that shows up occurs in the front buffer. I am ready and willing to do all that is necessary to get Blender working on this machine, so hook me up with an experienced developer, and I'll help out as much as possible.