Untrusted apps are not allowed to connect to or launch Window Server before login.

Question

I'm getting this with the Citrix Receiver uninstaller from the command line... but not on all Mountain Lion 10.8.5 systems.  Googling turns up a lot of ideas about a problem with the app or in pre/post-flight scripts, but since it works on some, I wonder.  What is the mechanism that generates this error?  I'm guessing there's some setting or condition that exists on one system that isn't true on the other.  How do I find out?
Sep 25 10:55:21 palms sudo[74325]:  joliver : TTY=ttys000 ; PWD=/Users/joliver ; USER=root ; COMMAND=/Volumes/Citrix Receiver/Uninstall Citrix Receiver.app/Contents/MacOS/Uninstall Citrix Receiver --nogui
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: 3891612: (connect_and_check) Untrusted apps are not allowed to connect to or launch Window Server before login.
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: kCGErrorFailure: This user is not allowed access to the window system right now.
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: _RegisterApplication(), FAILED TO establish the default connection to the WindowServer, _CGSDefaultConnection() is NULL.
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: kCGErrorInvalidConnection: CGSGetEventPort: Invalid connection
Sep 25 10:55:21 --- last message repeated 3 times ---
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: CGSRegisterConnectionNotifyProc called with invalid connection
Sep 25 10:55:21 --- last message repeated 2 times ---
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: kCGErrorInvalidConnection: CGSGetDockRect: Invalid connection
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: CGSGetCurrentDisplayMode: Invalid display 0x00000000
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: kCGErrorInvalidConnection: CGSGetCurrentCursorLocation: Invalid connection
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: CGSGetDisplayBounds: Invalid display 0x00000000
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: kCGErrorInvalidConnection: CGSGetCurrentCursorLocation: Invalid connection
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: CGSGetDisplayBounds: Invalid display 0x00000000
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: kCGErrorInvalidConnection: CGSGetCurrentCursorLocation: Invalid connection
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: CGSGetDisplayBounds: Invalid display 0x00000000
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: kCGErrorInvalidConnection: CGSGetCurrentCursorLocation: Invalid connection
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: CGSGetDisplayBounds: Invalid display 0x00000000
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: kCGErrorInvalidConnection: CGSGetEventPort: Invalid connection
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: kCGErrorInvalidConnection: CGSSetConnectionProperty: Invalid connection
Sep 25 10:55:21 palms Uninstall Citrix Receiver[74326]: kCGErrorInvalidConnection: Error enabling suspendResume handling

Answer 1

Contact Wacom. Unless they have updated drivers there is no workaround.
Update or remove Quicksilver.
Repairing the Hard Drive and Permissions
Boot from your OS X Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Installer menu (Utilities menu for Tiger and Leopard.) After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer. Now restart normally.
If DU reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.