Icons on the Tool bar disappear

Hello,

I'm not sure this is the right forum, but I cannot find any one which appears more suitable. I'm having problem with Acrobat X Pro. Everything works fine, but it randomly happens that the icons on the top menu bars disappears when I drag the mouse pointer over them. Once this thing starts I cannot use anymore Acrobat and the only way to restore it is to kill the program (End the task from the Windows task manager). Can anybody help ?