Hello, my name is Dan.
I will do my best to help you, the only stupid question is the unasked one.
There are a few other things to do before throwing in the towel.
Try a pram reset, followed by a safe boot. If you are using a USB keyboard it becomes much easier.
To do a PRAM reset, you need to restart your machine and hold down these 4 keys.
‘Option’, ‘Command (Cloverleaf or Apple)’, ‘R’ and 'P'.
Keep them down until you hear 4 startup chimes, this is the sound that your computer makes when it starts up, it is like a boonngg. The screen should also cycle from white to black and then back to white along with the chimes.
If you have a wireless keyboard then the procedure is a little bit different.
Use the very same keys but wait until the first chime and immediately press and hold those keys. I recommend getting your fingers ready because timing is critical.
This resets all of the system buses on your computer, USB, FireWire, display, ethernet and your keyboard/mouse/trackpad.
This will correct many faults but not necessarily yours.
As soon as you let go of those four keys press and hold the shift key for a safe boot.
To do a Safe Boot, restart and before the first chime press and hold the 'Shift' key.
Wait until you see the Apple logo and the spinning gear appear, then let go.
It can take as long as 20 minutes to load, so please be patient.
When the login screen appears it will say in red on the login window 'SafeBoot'.
Now login and give it a few more minutes to finish loading.
Try doing whatever it was it was giving you the problem. If it works then probably the problem is solved, so restart normally.
If the problem persists then restart normally also, other fixes will need to be done.
Then I suggest repairing the permissions.