Markgc--After digging very hard through your posts, do I understand that you have Acrobat v4 installed and think you also have Acrobat Reader v5.1 installed? Since Acrobat includes Acrobat Reader, and I gather you have not uninstalled Acrobat v4, that might explain your problem.
See my earlier post on uninstalling Reader (hopefully only Reader). Then maybe you can keep Acrobat 4 and install and use Reader 5.1.
Perhaps the folks at Adobe Forum can help.
http://www.adobe.com/support/forums/main.html