Things I would check: Set an arbitrary key like control or 1 or G to be your broadcast key. Make sure you're saving your settings and reloading the configuration or restarting the synergy server to apply your configuration changes. Make sure both WoW Windows have focus. See if there is any errors being logged that may give you a clue. I was never able to fix my spinning mouse and this is what eventually pushed me to Keyclone. You have to purchase a license for each machine and you won't be able to share a mouse, but it definitely made my life easier and much more stable.