Problems opening pdf, Word, Excel files from email attachments

Hi,
I need some help. For the past weeks my MAC will not open .pdf, Word, Excel files that I received as email attachments. I can save them, and they show the Acrobat Icon, which is my default program to use with pdf. (same for Word and excel files, the icons are there).
I have tried:
- open the files with double click from the desktop
- click the file icon, then specify which program to use to open
- open the application and click "File" and "Open".
- uninstalled and reinstalled Acrobat Pro and MS Office
- ran Utility "Repair Permissions" & received the following message: SWD file "System/Library/CoreServices/RemoteManagement/AADAgend.app\Contents/MACOS\AADAgent" has been modified and will not be repaired

I have no idea if this message has anything to do with my problem, or if it indicates another problem.

Does anyone have some advice? I am definitely not a computer tech, and appreciate any help.
Thanks,

You gave us a lot of information there, but you did not indicate the versions of your software, including the OS. That might be helpful. Also, do the Word files have a .doc suffix or .docx? Do the Excel files have an .xls suffix or .xlsx?

And for that matter, can you open the PDF files with Preview? That would help to determine whether the problem is with the file or with Acrobat.