Did you try to uninstall reader 9 and then reinstall 9?
You may want to try to uninstall Reader 9 download and install Reader 8.1.3 from http://get.adobe.com/reader/otherversions/.
I am having the same error on Vista and, like you, I am an administrator (it's my personal laptop). I followed the instructions here:
...(not noticing that that solution addressed the Program Data folder, not the Program Files folder), and it didn't work, but I wonder if a similar procedure on Program Files would work. But I don't know anything about theVista security system, so I'm a little wary of trying it. Would appreciate any thoughts.
And I just tried changing the owner of the Program Files folder to Administrator, per the KnowledgeBase fix, but it told me I didn't have permission to *change* the owner of that particular Adobe Reader folder...