Thanks to user Hotel Bravo who found this workaround. I've found a solution! Well, sort of -- it's a workaround, but it solves the issue.      
I recently installed the DDM (Dell Display Manager) 2.0 application on my new laptop. It's a nice upgrade from the original DDM. My problem with it, though, is that somehow it has stolen my Alt + S shortcut key, which I use in several other applications including sending email in Outlook.  I've gone into the settings and configured every shortcut I could find so it didn't conflict with existing shortcut keys, but I cannot find where the Alt + S shortcut is listed, nor how to change it so it doesn't conflict with other programs.  If I close out of DDM entirely from the task tray, my Alt + S shortcut key comes back. So I have to make a decision between having DDM open and using my Alt + S shortcut.  How do I fix this?
U4320Q, DDM 2.0, taking Alt + S shortcut