When I'm working in Adobe LiveCycle and click the preview tab to preview the PDF I'm working on, it launches in PowerPDF instead of Acrobat, which I wouldn't mind if it didn't take significantly longer to preview. I have my default program for PDF files set to Acrobat, so I'm not sure what to do to fix this. I'm on Windows 7 64bit, LiveCycle Designer ES2, Acrobat X and PowerPDF 1.0.
try to register Acrobat as default PDF viewer again.
Close Designer, open Acrobat.
Goto Edit > Preferences > General and click on Select Default PDF Handler.
Select Acrobat and conform with Apply.
I don't know PowerPDF but you should ensure that your browser will use the Adobe Reader Plugin for viewing PDF's online because Designer's preview is using such Plugin.
Thanks, that helped. My situation was that Adobe Acrobat Reader DC was being used by Designer via the Preview tab instead of Adobe Acrobat XI. I understand this was because the system saw Adobe Reader DC as a higher version over Acrobat XI, but I didn't know how to switch it back to Acrobat.