So what you're saying is that you tested in another user and it is the same?
How much available disk space do have left? If you're not running low on space then try a re-install the OS...
Boot up holding command-r keys into your Recovery Volume.
The screen should give you these choices...
Restore from TM backup
Reinstall Mac OS X
Get help online
First run Disk Utility Repair Disk, if you get errors run until no errors reported or reports "the disk cannot be fixed". Then, choose Reinstall OS X. This will be an install "in place" and shouldn't effect any of your own data or settings.