First, close all other programs (except this page so you can read along, or print it out and close your browser, too) and open Adobe Reader in your computer.
Second, choose Edit, then choose Preferences from your menu bar, then along the side of the dialog box for Adobe that opens, choose Internet. It will open a dialog box containing check boxes for "Allow fast web view" and "Allow speculative downloading in the background." Uncheck both of these boxes, then click Okay at bottom.
Apparently it is these two options, when checked on, that cause the computer to continue to run Adobe on ever increasing amounts of RAM until your entire CPU is tied up and made useless for anything else, even when no PDF files are being downloaded any more. Unchecking those two boxes allows the computer to continue to multitask even when opening giant PDF files like HR 3200.
If you find yourself in a PDF disaster/lockup before you get to these steps, ctrl-alt-del, select Processes, and delete acrord32.exe if you see it using 95 to 100 percent of your RAM in the CPU column. (Nik Colman authored this solution.)