Short cut key problem

My shortcut keys sometimes don't work. For example, H= Hand Tool, V= Move Toll, Save a copy=ctrl+alt+s works when pressed. Sometimes it's okay on its own. Which makes me very boring at work. Do I have a solution to this problem, if there is a solution, someone will please let me know that I will be benefited. (Note: I've installed and unstilled Photoshop a few times.)