Using Windows 7?
as Microsoft will stop supporting Windows 7 on Jan 14, 2020, so will Quark.
For Microsoft's timeline please see here:
https://support.microsoft.com/en-us/hel ... fact-sheet
This also means that any new version of QuarkXPress released in 2019 (or after) will not support Windows 7 anymore.
And if you are using Windows 7, please seriously consider to upgrade to Windows 8.1 or Windows 10 now; in any case no later than January 2020.