Fixing the PDF preview issue in Outlook

I was facing this problem where every time I tried previewing a PDF file in Outlook 2013, I get the message
"This file cannot be previewed because of an error with the following previewer:
PDF Preview Handler for Vista
To open this file in its own program, double-click it. "

I tried googling several sites and most of them said to try this fix: http://www.howtogeek.com/howto/7682/how-to-fix-pdf-previews-in-outlook-or-explorer-on-64-bit-windows/

I tried it  (both the manual registry fix, and the exe file which did the registry fix) but unfortunately, it didn't solve the problem for me. Then I saw another site that said upgrading the Adobe Reader to the latest version would fix it. I was using Adobe Reader v10, and there was a version XI available. When I've done with upgrade, I then got this message in Outlook:

"This file cannot be previewed because there is no previewer installed for it."

 I then tried checking the preview add-ins in Outlook via File>Options>Trust Center>Trust Center Settings >Attachment Handling>Attachment and Document Previewers and couldn't find any PDF Preview Handler value there.

Further searching on the web led me to the only working solution I can find so far: http://social.technet.microsoft.com/Forums/en-US/outlook/thread/203d7369-b11c-4b9c-a90c-729f1776bd65

The fix is simply to reset the preview option for Outlook via modifying the registry via regedit. All you need to do is change in the registry the key HKCU\Software\Microsoft\Office\Previewers\pdf\PONTState value's data to 0 to re-enable the "always warn before previewing" for pdf attachments.

 I finally managed to preview PDF in Outlook. FYI, I'm using Windows 7 x64 with Office 2013.