Did you look here ? https://support.mozilla.org/en-US/kb/view-pdf-files-firefox-without-downloading-them The last section "If PDF files are downloaded instead of displayed, try these solutions" seems to concern your problem.

If it doesn't work, maybe installing a pdf viewer could solve it ? Back to the link, the middle section talks about it too.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

You can rename (or delete) the mimeTypes.rdf file in the Firefox profile folder to reset all file actions.

• http://kb.mozillazine.org/mimeTypes.rdf
• http://kb.mozillazine.org/File_types_and_download_actions#Resetting_download_actions

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Success! Thanks, Gnarrrk!

Thanks for the reply, cor-el. Turns out I didn't need to try your suggestions but they may help someone else down the line (or me if I run into this problem again).

Note that your System Details List shows two Adobe Reader plugins.

• Adobe PDF Plug-In For Firefox and Netscape 11.0.9
• Adobe PDF Plug-In For Firefox and Netscape "9.5.5"

You can find the installation path of all plugins on the about:plugins page.

• http://kb.mozillazine.org/Issues_related_to_plugins#Identifying_installed_plugins

Now hang on a second! How is it that you're reading my System Details List? I don't like this one bit and I'll thank you to stay out of my browser set-up.

You're welcome. And it's better that Cor-el reply too, cause he is infinitely more experienced than me. ;) Also, as he noticed, you have a lot of addons. Maybe a lot of programs installed and running under Windows too ? Computer sometimes a little slow ? Maybe a little cleaning (like with ccleaner) could be useful... And checking in Firefox if you really have the use of all the plugins and addons installed. As we have some addons in common, you could be interested by : - greasemonkey (anti-adblock killer Reek + youtube autoplay disabler) - lazarus : form recovery - noscript + redirect cleaner + self-destructing cookies + smart referer + wot - tree style tab + hide caption titlebar plus Enjoy !

Thanks, Gnarrrk. Actually, I do use CCleaner fairly often. My computer isn't slow but Firefox sure can be at times! When it needs over a Gig of RAM, something's wrong. Rebooting it solves that... for a while.

A lot of the plugins I have installed run only when called, so they're not active all the time. And given your and cor-el's concerns about how many plugins I have installed, your recommendation to install more is a little funny. Well intended, I'm sure, but ironic nonetheless.

What REALLY concerns me, though, is how you and he were able to see which plugins I have installed. Maybe that's part of the terms of service for Mozilla Support but it's more than a little creepy, given all the hacking that's going on on the web.

Part of the AAQ (ask a question) process is to ask if you want to supply troubleshooting information. Acknowledging this will install the Troubleshooter 1.1a (troubleshooter@mozilla.org) extension that also appears in the System Details, so it is likely that you have approved this. If you click the "More system details" link in the menu at the right of your first post then you can see what is send.

See also:

• https://support.mozilla.org/kb/Using+the+Troubleshooting+Information+page

That explained it. Thanks!

I didn't mean to be ironic, but ok. ;) The more recent your computer is, the more addons you are able to install on your browser. This was why I asked first if your computer was slow. Then, it's better to choose the right addons for your use, and delete the unnecessary ones, for your browser to work better.

And, it is a good thing that you realize how easy it is to see what are the informations leacking while you're surfing. Test this : https://panopticlick.eff.org/ and enjoy ! :p