Problems opening pdf files

I have a MacBook using 10.5.8. I can no longer open a pdf file. I have both preview and adobe operational. This has been going on for several months, and perhaps started with a recent software update, I don't know.
I took it to the Genius Bar, and no one could help. Any ideas??

Welcome to Mac-Forums

What happens when you try to load the PDFs? Are these PDFs that others can open without any problems? Is it only PDFs that Preview fails to open but can open other files without any problems?

When I try to open a new pdf file, the screen just goes blank and nothing happens. However, if it is a pdf file that I have opened in the past, I can open it.

Yes, if I go to another computer, these files can be opened.

It sounds like Adobe has disabled Preview from opening PDFs and made itself the default for doing so. Preview will still open those PDFs it opened previously.

Right click on a PDF file, select "Open With" and try setting Preview as the default for opening all PDF files.

pdf

Thanks for your input. When I right click I get the following options:
Open Link in New Tab
Open Link in New Window
Bookmark this page
Save Link as.....
etc

If I go into Save Link, it had defaulted to *.pdf; when I changed it to "All FIles" I just got one to file to open, and one did not.

So, do you think I have somehow have changed Adobe to my default? Any ideas how to correct that?

Thanks again!
Cool airplane!

Don't right click on a PDF file in your browser. Follow my directions, but do it from the Finder. Also, if you're using Safari, you can go to add ons and disable Adobe. That will make Preview the default in both Safari and from Finder.

Thanks very much. I have run out of time today but will work on it again. Some of what you said, I had success in Safari but not in Firebox. I'll keep at it! Thank you