Under normal circumstances, when you quit out of QuarkXPress, the operating system flags that the resources that link the application to the XPress Preferences file to be released. When QuarkXPress quits or crashes, this cannot occur. Upon an attempt to re-launch the application, the XPress Preferences file is still being read as “in use.” This is what is causing the error to be displayed.

To resolve the issue, use one of the solutions listed below:

Solution 1:
Restart the machine. This will release the current XPress Preferences file.

Solution 2:
Create new XPress Preferences. To do so, use one of the following procedures:

  1. Navigate to Mac Hdd\ Users\ Current User\ Library\ Preferences\Quark. Rename the QuarkXPress 9 folder as Old QuarkXPress 9. Always rename the folder so that, if required, you can revert back to the old XPress Preferences

    For 10.7.x & 10.8.x:
    (On the Finder window, please press and hold the 'option' key (marked ALT) and on the menu bar, at the top, select Go to view the User Library)
  2. Navigate to Mac Hdd\ Applications\ QuarkXPress 9.x and create a new “Preferences” folder