i tried re-installing yosemite and was able to get preview/iphoto to work, but a couple weeks later it happened again (just get a transparent box of where the window should be) .. googled that is was OpenGL issue, notice that the OpenGL.bridgesupport file had different (newer) last modified date than the rest. I re-installed yosemite 10.10.2 again, and noticed it was now last modified with an older date than the rest of the files (preview/iphoto worked again). i found it in system/library/frameworks/OpenGL/Resources... couldn't upload .bridgesupport file...but re-installing yosemite did re-initialize to file with older date... my mbp is 2009 17" - nvidia 9400M... it only supports up to 3.2 version of OpenGL... it looks like this file maps versions to make them backward compatible etc... I'm no expert, and I'm not sure this is actually why, maybe just lucky coincidence
.. thought it might help