I'm going to have to figure out how to do the new OS X install over the next few days - I'll keep you posted.

I would suggest if you haven't already done so, that the first thing you should do is to create a backup of your data assuming you want to keep it all.

After you have a current backup, then you can proceed with installing a new OS X.

I would suggest doing what I suggested in my post #8, then boot up using your Recovery HD and use the reinstall option to install into the new bare partition.

That should at least give you a pristine OS X to boot from and confirm the Mac is all working properly — or not.

If it doesn't, there are more serious problems to be dealt with.

- Patrick