On our enterprise network I have found that suddenly folks cannot display PDF's in the Internet Explorer 7 browser.
The software and versions that are affected are:
Adobe Acrobat Pro 8.3.3
Adobe Acrobat Pro 9.3.3
Adobe Reader 9.3.3
Troubleshooting steps I have done:
Unchecked the option to Display PDF in Browser and rechecked it/
Completely uninstalled Adobe Pro/Reader has no effect. This includes deleting all files in c:\program files\Adobe\ and c:\program files\common files\Adobe\Acrobat\
Rebooting then manually reinstalling.
It behaves the same for Adminstrator accounts.
I have deleted the AcroExch.Document registry key and then repaired Acrobat to replace it.
Not sure what else to try. Is there a registry fix or could this be set by a Group Policy? I assumed that if it was a Group Policy then it would just uncheck the 'Display in PDF Browser' option in Adobe preferences. Even if that IS checked, PDF files still open outside of Internet Explorer.
Also note: we have Internet Explorer 7. Enable 3rd Party Browser Extensions IS disabled by a Group Policy but I think that only affects the Acrobat Toolbar from being implemented, not displaying PDF in a browser.
Any other helpful suggestions on what to try next would be appreciated.
Found the problem. It was a McAfee Host Intrusion Prevention Policy that was blocking it. Once that was updated, PDF files could display in IE.