Hello! I have Windows 7, 64 bit, Firefox 20.0.1 and Internet Explorer 9.0.8112.16421, both with the same problem. I have Adobe Reader 11.0.2. Earlier today I was able to open PDFs in the browser tab, this evening not so much. I am not sure what changed - to my knowledge I didn't get anything updated today. I have checked all my settings and can't figure out what's wrong. I've uninstalled and reinstalled the program. The only thing I couldn't find after extensive Googling of the issue is that my Adobe Reader lacks the button that is referenced in a lot of posts for "display PDF in browser" is missing. I've included a screenshot.
In addition, in Firefox there used to be an option "Use Adobe Acrobat (in Firefox)", but now there's just "Use Adobe Reader (default)" or other pdf readers (and I *hate* Firefox's pdf reader). I haven't gone too deep into IE's options since I don't use it hardly at all.
Any help would be greatly, greatly appreciated!
Thanks
Linda