FYI, getting the same problem on 10.7.4, which, when I go to the login screen any time after connecting a DisplayLink device, the system beachballs and I cannot log on anymore, to the point that I have to hard-power off the Mac and reboot it.
Code:
9/21/12 2:47:37.439 PM DisplayLinkManager: 3891612: (connectAndCheck) Untrusted apps are not allowed to connect to or launch Window Server before login.
9/21/12 2:47:37.439 PM DisplayLinkManager: kCGErrorFailure: Set a breakpoint @ CGErrorBreakpoint() to catch errors as they are logged.
9/21/12 2:47:37.476 PM DisplayLinkManager: _RegisterApplication(), FAILED TO establish the default connection to the WindowServer, _CGSDefaultConnection() is NULL.
9/21/12 2:47:37.476 PM com.displaylink.usbnivolistener: _RegisterApplication(), FAILED TO establish the default connection to the WindowServer, _CGSDefaultConnection() is NULL.
9/21/12 2:47:37.479 PM DisplayLinkManager: SCNetworkReachabilityCreateWithAddress[Pair] called with invalid address family 1