What exactly do they mean by exiting all other applications? What constitutes an application? Technically, any software executing in a thread is an application. Software drivers could constitute an app, strictly speaking - the driver for your camera, printer, microphone, network card. What? That means everything - all those little icons in your tray (or Notification Area as they call it now), what about Windows Services? So they want me to shut down Windows before continuing!?!? I don't get it.
Second, WHY?? Why oh why does it say that? I mean, really, if I don't shut down other applications, what will happen - is it going to make my computer run slower each month? (Already happens - it's Windows for God's sake.) Is it going to make it unstable and crash a lot? (Already happens - IWFGS.) Is it going to refuse to install the app? (Hasn't happened yet - IW...never mind.) Really, people, let's just get out of the dark ages 30 years ago when you were running only one program at a time, and you HAD to shut down all other programs in order to install.
By the way, who are "people"? These "people" are a company currently called Flexera (http://www.installshield.com), the company tasked with making the Windows Installer component. Let's start a campaign! Everyone, fill out their online contact form - ask them to rewrite the installer messages to be more up to date, and user friendly!
Flexera Software
1000 E Woodfield Road, Suite 400
Schaumburg, IL 60173
http://www.flexerasoftware.com/company/contact-online.htm