Thanks, SumatraPeter; great minds think alike :). The Manage Add-ons was the first place I looked, and Adobe is NOT listed! Go figure. I may just uninstall Adobe altogether and see what happens. Windows is using Sumatra fine for computer-based pdfs, and Firefox uses it’s own viewer, so that’s fine.
I did miss (if it ever showed) an Options button, and frankly, it’s hard for me to understand my missing it since I’m one of those annoying geeks who wants to customize everything and so always look for Options :). Oddly, just dragging the whole Sumatra folder from Program Files to my custom folder seems to have worked, although I’d think it shouldn’t; I didn’t choose the portable version, so usually just moving a folder doesn’t cut it.
When I’m feeling adventurous, I’ll uninstall Adobe and see what happens with IE, and report back here in case it helps someone. Just thought there should be an option in Sumatra to enable it in IE (as there is with FoxIt.)