When you install ExtraPuTTY, it creates a shortcut in the start menu to the Examples folder, and in the shortcut properties it defines the hotkey Control+Shift+Z to run/launch it.
To solve this issue, you can go to:
%APPDATA%\Microsoft\Windows\Start Menu\Programs\ExtraPuTTY\Examples
(for example, it will look like this, with "charles" replaced with your windows username):
C:\Users\charles\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\ExtraPuTTY\Examples
Then right-click on the Examples shortcut in that folder
Click Properties
Click inside the Shortcut Key box.
Press Backspace (or Delete) to clear the shortcut.
Click OK.
To avoid this issue:
When you're installing ExtraPuTTY, you can deselect the option to install Examples.
Tested with both the snapshot version of ExtraPuTTY (ExtraPuTTY-0.30-2016-04-04-installer), and the release candidate version (ExtraPuTTY-0.29-RC2-installer).
I'm submitting this as an official bug as well, but it looks like development has been stalled for a few years. Thus I'm posting the info here for more general visibility.