Since upgrading to Adobe reader X, I am having problems previewing and opening pdf attachments within the Microsoft outlook 2010. Searching through Adobe’s own forums and internet was waste of time as still it needs to be solved. you can access the topic at the following link: http://forums.adobe.com/message/3363074?tstart=1.
Now this is my solution which involves uninstalling Adobe reader X and reinstalling the older Adobe 9 version.
- First go to Add or remove programs (windows xp) or programs and features (windows vista or windows 7).
- Uninstall the Adobe reader X.
- Restart your computer.
- Download Adobe acrobat 9 from the following Adobe URL: http://get.adobe.com/reader/otherversions/.
Once Adobe reader 9 was installed, I was able to open and preview a all my pdf attachments in Microsoft outlook 2010.
Hope you find the topic helpful and thank you for reading.

What a good and revealing post.
Sadly this is the only thing that worked for me too. The other advice to disable protected mode at startup doesn’t help with Outlook 2010 on WinXP. Thanks a lot Adobe..