I looks like you're missing at least one core UI file from the default UI (and also possibly from the custom UI you're using).
Make sure your custom UI is the latest version. If the custom file doesn't exist for the Hotbar Settings window, you should be seeing the default window, which you're not. This indicates that your default UI directory isn't quite up to date.
I recommend running a full file scan just to make sure nothing was missed or corrupted. (Load up the launchpad and login, then click "Preferences" > "Full File Scan.")
|