Please test the the software after each one of these steps is completed.
Make sure your Mac's OS is fully updated. If possible, update to the latest available OS version.
Delete, download, and install the latest version of the Fretlight Studio from the following link. Make sure no antivirus, malware, or firewall programs are running during the installation.
Run Mac's Disk Utility to check out your hard drive and "Repair Permissions":
Boot up your computer while holding down Command+R (if you're running Snow Leopard or earlier, find your OS installation disc, put it in the drive, and reboot your computer holding down C). This will boot you into a diagnostic mode.
Select the Disk Utility Option.
Select your hard drive, and click "Verify." Wait for Disk Utility to finish running.
If problems pop up, click "Repair Disk."
If nothing pops up, click "Repair Permissions" and wait for Disk Utility to scan your hard drive again.
If Disk Utility finds and repairs some problems, go ahead and reboot.
If you are running 10.10+ you can also try one of the the following free Mac cleaner/fixer programs.