Windows 8 [HELP] I can not type in app in randomly manner

[Rangga Pradipta Dwitiya]

I am using a windows 8.1 version. When I am typing in app (ms word or even mozilla) suddenly I can not press any input. It seems like I got kicked by the app to return to the desktop but not minimized the app. When I press any input it making the usual wrong input sound from windows.

Please help me it get so annoying when I am writing or even doing anything with my apps.