I believe 5.5 is not supported - you'll need to revert your OS.
InDesign CS5.5 is most definitely NOT supported on Yosemite. You might get it to run, but there is no guarantee, or that all features will work, and you are entirely on your own.
Absolutely unsupported. That said, if you did an in place upgrade, which I
suspect is the case, I would uninstall, run the cleaner tool and then
A live sacrifice might also help. Apple has never cared about backward