Q: Why does my itunes close immediately upon start?

When I tried to open it, I can see the icon in my task bar below, but then it disappears almost immediately. The apple icon is now on its own trying to open, and shutting itself down.  I tried removing the config/pref files like apple support says, I tried re-installing both itunes AND quicktime, it's not blocked by my firewall. I've tried restarting my computer. I don't know what to do next. Any suggestions?