hi, I have been working to do the same thing on a windows 10 machine but to little success. On an up side I know how to do this for windows 7(Tried and tested).
a. Click Start, Run, type “regedit”.
b. Navigate to "HKEY_LOCAL_MACHINE->SOFTWARE->Policies->Microsoft"
c. Create a new key of name "KeyboardFilter"
d. with keyboardFilter selected create a new string value named "Shift+Ctrl+Esc"
e. set this new key to the value 1 and save.
*this can be done for many shortcuts such as Alt+Tab , Win+R
f. next you will need to run command prompt as administrator. (Win+R type cmd, check box to launch as admin)
g. type "sc start KeyboardFilter" into command prompt and press enter.
f. Test your keys are disabled.
*if when you run the command prompt process you are told this service is already running sometimes you need to restart the process for it to take effect. To stop the service type "sc stop keyboardFilter" and enter. This will stop the service so now repeat step g.
Hope this helps you out and if anyone has any tips on doing the same thing on windows 10 id appreciate it because my understanding is they decided to remove the keyboardFilters service from windows 10.