Windows (or my video card software) takes over applications' shortcuts, what to do?

I'm working with different applications (Notepad++, Visual Studio), where I regularly need to perform a search. As this involves C# source code, it's important to search for whole words, case insensitive. In order to do this, I regularly use the shortcut Alt+W (for whole words) and Alt+C (for case sensitive), shortened into Alt+W+C . Since recently this does not work anymore, as this shortcut seems to be taken over by Windows or by my video card software, causing one of my screens (number 2 ) to be shut down (I call it shut down , I mean that the monitor pretends not getting info anymore, like

Question by Dominique on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.