No. I can get into Adobe Reader preferences. The checkbox specifying open pdf files in browser is checked as default, but grayed out and I cannot change it. So there is no way to open all pdfs in Adobe Reader; the default is to open them in a browser, and my default browser is Firefox...which corrupts some pdf ebooks, making them unreadable. Safari does not corrupt documents, but normally I don't use Safari. I've spent some hours searching online and reading discussions, but haven't found a solution. At this point I feel this issue has consumed far too much of my time. I can get by with klunky performance and frequent extra steps...easier than continuing to try to find the elusive solution.
The checkbox specifying open pdf files in browser is checked as default, but grayed out and I cannot change it.
You are correct. If you really don't want the Reader to launch in Safari, shut down Safari. Go to the /Library/Internet Plug-Ins/ folder and remove the following two files:
You may need to enter your admin password to complete the operation. If you check the Reader's preferences after that, you'll note that the check box is now off, though still grayed out.
Note though that this will not prevent PDF files from displaying in Safari since Safari itself will do that. This is assuming you are always doing a standard left button mouse click on any PDF link. In which case, the default is always to display the PDF file in the browser.
There is no way to open PDF files online directly into the Reader or Preview. You can wait until it finishes loading in the browser. Move towards the bottom of the screen and you'll have these choices (without the Adobe Reader plug-ins active):
Click on the third icon, which looks like a loupe on some paper. The PDF in the browser will then open into your default PDF viewer. Your only other option is to right click on a PDF link and choose Download Linked File, or Download Linked File As to save the PDF to your hard drive. From there, you then open it with the Reader.
Neither is what you want (opening a PDF online directly into a browser), but as I noted, it can't be done. The browser is the application with direct access to the online source, not the PDF viewer, or any other app.