Why does my keyboard keep flashing/disappearing?

[AC Question]

Whenever I'm on Facebook or Twitter, (not the apps) and I attempt to type, the keyboard will do one of two things: it will either begin flashing rapidly so that nothing else can be typed or it will disappear altogether. Is anyone else having this problem? Does anyone know how to solve it?

 

[Javier P]

Which phone and keyboard are you using? Does the same happen with any other app or just those two? Which browser are you using?