I use an IDE that wants to use Ctrl-Alt-V as a keyboard shortcut.  That keystroke is already bound  in systemsettings to the Blobal Keyboard Shortcut to the component Plasma Desktop Shell as the "Systemtray-Klipper-8" action.

So I go in to system settings and configure Systemtray-Klipper-8 to have a custom shortcut which I make "None"., click apply and then close system settings.

Every thing works fine, my IDE can see the keystroke and execute its command, until the next reboot.  The the keystroke is bound to Systemtray-Klipper_8 again and I have to go through the rebinding after each reboot.

Reproducible: Always

Steps to Reproduce:
1. Hit CTrl-Alt-V.  Notice that the Klipper menu opens up.
2. Open systemsettings->Shortcuts and Settings->Global Keyboard Shortcuts
3. Select the KDE component "Plasma Desktop Shell" (you need to scroll down to find it)
4. Note that Systemtray-Klipper-8 is bound to Ctrl-Alt-V.
5. Change the binding to a custom binding and make it None.
6. Click apply.
7. Hit Ctrl-Alt-V and see that the Klipper menu does not open.
8. Reboot and login
9. Hit Ctrl-Alt-V and see that the Klipper menu does open.
Actual Results:  
After rebinding Ctrl-Alt-V to None and a reboot, the Klipper menu opens after pressing Ctrl-Alt-V.

Expected Results:  
After rebinding Ctrl-Alt-V to None, the Klipper menu should NOT open after pressing Ctrl-Alt-V, even after a reboot.

After further testing I found that restarting kded4 will also tickle this bug.  You don't have to do a full reboot.