When I open a new or used excel file. Sometimes it does not allow me to do anything, but only to minimize or close it. Once I minimize and open it back up. Everything works. The excel files are used by other members and no one else is having this problem. I can work on a excel for a few hours and close it for lunch, go to re-open it and nothing. Until I minimize it and open it back up.

I have Google and searched, i cannot find anything. Does anyone know anything?