I recently leapfrogged from Tiger 10.4 to Mountain Lion 10.8 and bought Pages, Numbers, and Keynote. Today, I proceeded to download the User Gides.
From the Pages/Help menu, I chose Pages User Guide. It opened a window in Safari and a progress bar started. When it was done, I had what appeared to be a PDF document in the window, much as if I had downloaded some PDF from a vendor website. As I have done many times before, I selected File/Save As and put the PDF document on my Desktop.
The resulting file has a Preview icon and a .pdf suffix but, when I double click on it, I get the message,
"The file “Pages09_UserGuide.pdf” could not be opened. It may be damaged or use a file format that Preview doesn’t recognize."
If I try to open the file from within Preview, I get the same message. If I try to open the file from within Acrobat, I get the message, "There was an error opening this document. The root object is missing or invalid."
So, I went to the Apple Support site, Manuals, and located the Pages 09 User Guide and downloaded from there. To my surprise, it did not download into my Downloads folder but, again, opened a window in Safari and i went through all the same processes with all the same results. I tried the Numbers 09 User Guide with all the same results???
So, I did an Apple Support call where the tech finally resorted to getting the setup where she could see my screen and we went together through all the same steps with all the same results??? What the heck is going on? I hope I'm not going to find that I have to download into Safari everytime I want to refer to the User Guides for this software!
In your browser go back to Apple Support Downloads area for iWork manuals.
On the manual of your choice, use your right-mouse button (trackpad: two-finger tap) to bring up the menu, and select:
Download Linked File as ...
Now you can put that PDF anywhere you choose, and open it directly with Preview.