Looked in forums, no help. I've uninstalled, re-installed application twice, also repaired it. No help.
Acrobat 9 Pro, Win 7 (64bit), Norton security.
Please delete all files inside the "C:\Program Files(x86)\Adobe\Acrobat 9.0\Acrobat" directory and then run Repair for Acrobat from "Control Panel -> Add and Remove Programs".
To delete the files you will have to launch the command prompt with Administrator rights, for doing so you should go to Start->all programs->accessories" and now right click on the command prompt which appears in the list and click on "Run As Administrator".
You can also delete the files by manually going to the above mentioned directory (i.e C -> Program Files(x86) -> Adobe -> Acrobat 9.0 -> Acrobat ) and now select all the files and delete. UAC dialog will be thrown to ask for the elevation, click yes on that. In this process some of the files may not be deleted but that is okay.
Now run repair for Acrobat from "Control Panel -> Add and Remove Programs".
When the core library does not work anymore, Acrobat / Reader can no longer run because the components it depends on do not load.
> Enable the hidden Admin Account on Windows 7 ( Ref : http://www.howtogeek.com/howto/windows-vista/enable-the-hidden-adminis trator-account-on-windows-vista/ )
> Disable all Non-Microsoft Startup Services. (Ref : http://helpx.adobe.com/x-productkb/global/disable-startup-items-servic es-windows.html )
> Disable all the Antivirus softwares temporarily from the computer.
This error is known for conflicting Antivirus softwares like CA, Norton,Mc Afee etc.
> Delete the all the contents in the locations mentioned in the doc :
Note: It's possible that your system doesn't contain all of the files and folders listed in this document. If you do not find a listed file or folder on your system, proceed to the next file or folder on the list.
> Reboot the computer and install Adobe Reader 11 and check
Ok...I installed Malwarebytes Anti Malware Corp, removed the viruses I found. Since this did not take care of the problem, I then went to the "more tools" section and installed the "Anti-rootkit" tool. Followed the instructions and finally removed all the malware found. I then rebooted the machine and viola! I am now able to open my PDF files.