My first guess would be that the culprit is a stuck key on the computer keyboard.

The key can be physically stuck.

To fix, try tapping the key several times until it is released.

Or the key can be electronically stuck.

To fix, try a computer reboot.

Tried re-booting a couple times.  No luck.  Any idea which key would be the problem? 

… The dynamics expression tool also isn't working …

… Any idea which key would be the problem? …

I suppose that you get “nothing but” one specific expression - right?

Which expression do you get?

Take a look in the Expression Selection, at the box showing the (only) expression you get.

Which computer keyboard key is displayed in the upper right corner of the box? (That key is the metatool trigger key)

Probably that key is the stuck key.

Do you have another keyboard you could try?

Did you actually shut down the computer, and then restart it? That’s more effective than a simple restart.