We recently upgraded our browser Internet Explorer(Standard browser for our organization) from IE 8 to IE 9 and since then just one user(not all) having issue opening few PDF documents.
In a same document library some PDF opens OK within the browser but for few documents, it throws an error "internet explorer cannot display the webpage".
It just fails to locate those some the PDF documents. When open in explorer view PDF documents opens OK, no drama. 

We tried to fix and upgrade adobe acrobat with no luck. 
When we roll back to IE 8 it fixes the issue. Also only one user is having this issue and we don't want to roll back to IE 8.

Our setup is following.
SharePoint 2010 Enterprise.
IE 9

It is very frustrating as some PDF works and some not. Running out of troubleshooting ideas. 
Any help would be highly appreciated.