You can sometimes resolve problems with Horizon Client by uninstalling and reinstalling the Horizon Client application.

You uninstall Horizon Client by using the same method that you usually use to uninstall any other application.

Drag the VMware Horizon View Client (Horizon Client 3.0) or VMware Horizon Client (Horizon Client 3.1 and later) application from the Applications folder to the Trash and empty the trash.

After uninstalling is complete, you can reinstall the application.

See Install Horizon Client on Mac OS X.