Hmm...maybe my Wacom tablet, maybe my webcam, otherwise I can't think of anything...but, my Wacom tablet has two buttons and a scroll wheel, and even my webcam has a snapshot button.
I'll unplug these devices to get it to run properly, but for now I can find errors with it/them...

OK, I'm past that error, now I get this:
Exception in thread "main" java.lang.NullPointerException
at org.jagatoo.test.input.InputTest.setupInputSystem(InputTest.java:384)
at org.jagatoo.test.input.InputTest.startLWJGL(InputTest.java:571)
at org.jagatoo.test.input.InputTest.<init>(InputTest.java:678)
at org.jagatoo.test.input.InputTest.main(InputTest.java:685)
EDIT: Ah, wait, I found what it is. I had a MIDI keyboard hooked up to my computer.
EDIT2: Actually, my Wacom makes this error too. Also, I get this error sometimes:
Exception in thread "main" java.lang.NullPointerException
at org.jagatoo.input.managers.InputStatesManager.updateState_(InputStatesManager.java:167)
at org.jagatoo.input.managers.InputStatesManager.internalUpdateState(InputStatesManager.java:202)
at org.jagatoo.input.InputSystem.notifyInputStatesManagers(InputSystem.java:188)
at org.jagatoo.input.impl.lwjgl.LWJGLMouse.collectOrFireEvents(LWJGLMouse.java:169)
at org.jagatoo.input.impl.lwjgl.LWJGLMouse.update(LWJGLMouse.java:276)
at org.jagatoo.input.InputSystem.updateMouses(InputSystem.java:1099)
at org.jagatoo.input.InputSystem.update(InputSystem.java:1142)
at org.jagatoo.test.input.InputTest.startLWJGL(InputTest.java:577)
at org.jagatoo.test.input.InputTest.<init>(InputTest.java:678)
at org.jagatoo.test.input.InputTest.main(InputTest.java:685)