Often, whilst working in Outlook, I will close it for some reason. Shortly afterwards, when I try to re-open it, it won't open. The problem is easily solved by going into Task Manager, where the program is shown as being still running, and ending the process. After that I can re-open it. I assume I could not re-open it in the first place because it was still running even when I'd closed it. How can I make sure that when I close Outlook it really does close, so that I don't have to go into Task Manager? Thank you.