Locate your GUNZ files/folder, usually located at :
C:\Program Files (x86)\GG\GUNZ
Right-click on the “gunz” application and hit “properties” as shown below.
Proceed to the “Compatibility” tab.
Select “Run this program in compatibility mode”.
Select “Windows XP, Service Pack 3 from the drop down menu.
“Disable full-screen optimisations”
“Run this program as administrator”
Repeat the exact same steps above with the “launcher” application, as seen below:
Hit "Apply" and OK.