What happens when you try?
Can you open it when you save it to disk first?
If so, you probably need to clean out your SecureTemp folder.
See
http://www.howto-outlook.com/faq/securetemp.htm
--
Robert Sparnaaij [MVP-Outlook]
Coauthor, Configuring Microsoft Outlook 2003
http://www.howto-outlook.com/
Outlook FAQ, HowTo, Downloads, Add-Ins and more
http://www.msoutlook.info/
Real World Questions, Real World Answers
-----
"Jon" <(E-Mail Removed)> wrote in message
news:816BD98A-0BF7-486A-B105-(E-Mail Removed)...
> After I moved an email message within the mail folders (MS Exchange 2007
> mail
> server), I could not open a .PDF attachment that was sent with the email
> message.
>
> Is this a bug?
>
> MS Outlook 2007