I had problems after upgrading to "yosemite" (a big mistake). As others have already said, you have to uninstall the current Java and reinstall Java 7, which I think they now call "legacy". I had a game expert/acquaintance do it. One option is get an on line expert, "presto Experts" for example, to do a screen share and do it for you. They charge, of course, in five minute increments , I think. This fix should not take more than ten minutes.