I got it to work!!!
Thanks Mohit and Pam_A for your support.
The Adobe support people directed me to some instructions to do manual removals of stray files and registry items that were lingering from old installations of Reader and Acrobat. After that I did a clean install and it worked!
Here is a list of files that helped me, for others that may have this problem:
"The Display PDF in Browser option controls the Preview Tab from within LiveCycle Designer. It is possible that there are Adobe Reader® registry keys that are left over controlling the preview tab and
causing it not to load.
Depending on what version of Adobe Reader you had installed, you will
want to do the instructions on the following documents:
Adobe Reader 8.x
http://www.adobe.com/cfusion/knowledgebase/index.cfm?id=kb400769Adobe Reader 7.x
http://kb.adobe.com/selfservice/viewContent.do?externalId=kb400728Adobe Reader 6.x
http://kb.adobe.com/selfservice/viewContent.do?externalId=327675<(>&<)>sliceId=1
Acrobat Reader 5.x
http://kb.adobe.com/selfservice/viewContent.do?externalId=327928The most important parts of these documents are the registry removal
sections. Be sure to delete the registry keys as instructed in these
documents."