Acrobat 9 Pro does not list MS Office files as supported files

Question

I've tried this on 4 different computers. All computers are running Windows 7 and Microsoft Office 2007. 2 of the computers are running Acrobat 9 Pro and 2 of the computers are running Acrobat 9 Standard. On two of the computers, one Pro and one Standard, if I try to combine files into a single PDF, it lists all MS Office documents as supported files. I can use Excel or Word to create the PDF. However, on the other two computers, again one Pro and one Standard, no MS Office files show up when I try to combine files into a single PDF. How can I fix this? I can Print to PDF using the Adobe PDF printer from Excel and Word on all 4 of the computers. And I've verified that the Acrobat COM Add-in is enabled and working properly. I've tried this on Acrobat 9.0 all the way up to Acrobat 9.5 with the same results. Any help would be greatly appreciated!

Answer 1

Ok, I now got to version 9.3.1
But the procedure was some kind of weird:
(I don't know if this is working everytime)
1.) Deactivating Antivirus and firewall
2.) Logging in as Administrator: Starting the manual update -> Known Error
3.) Restarting computer
4.) Logging in as User (with Admin-Rights): Starting the manual update
Now the installer reports a running installation (from the adminstrator-account)
and ask to remove it.
Now click "yes"
The installation proceeds successfully.