Hi,
I have an annoying problem with my Taskbar.. Sometimes, if I click an Icon (eg. Mozilla Firefox' Icon).. The icon seems clicked (Icon is focused), but the program never opens.. Next time when I click that icon, it works...

. This problem is not appearing everytime.. Wat should i do?..
NB: I've scanned my system with MS Essentials, Malwarebytes and found none.
Did SFC /scannow.. and found no integrity violations..
Plz help me...