Don't understand what you mean by "if quitting for no apparent reason is a problem with Yosemite". That seems to imply you are quitting an application, so one would think it would not be a problem.
While resetting the PRAM and/or SMC is, most likely, not applicable, you do need to follow what I said about booting to the Recovery Partition. Given that I suspect you do not have a more robust disk maintenance/repair program like Disk Warrior or Tech Tool Pro, Disk Utility is your only choice.