Keyboard Viewer crashes when I use keyboard command
After further investigation I found my startup drive was corrupt and I needed to run Disk Utility. Steps I took:


Delete com.apple.HIToolbox.plist from Library/Preferences/ folder.
Restart machine.
Hold down CTRL + R to run Disk Utility from Recovery HD.
Selected Disk Utility from Recovery HD menu.
Ran First Aid on my machine.
Once finished, I restarted.


After restart the issue went away.