User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:27.0) Gecko/20100101 Firefox/27.0 (Beta/Release) Build ID: 20140212131424 Steps to reproduce: Open Firefox on Windows. Open the attached file with the native pdf viewer. Actual results: Firefox starts opening blank tabs after tabs in a very rapid way and never stops. Click on the red cross to close the program does not work. Killing the process in the task manager stops the current thread, but then another thread spawns and reopens a firefox window that continues opening tabs. I've been lucky once and was oable to kill them both in rapid succession: that stopped firefox for good. When I opened firefox again manually it behaved properly. Expected results: Firefox should have displayed the file. I loaded this file on libreoffice and it displayed fine, so I'm sure this is a valid file.

I experience a similar problem where an image file is saved (for whatever reason) as a pdf AND .pdf extensions are opened with firefox as the default, the tabs will open as described above. In windows explorer the file type was described as a Firefox HTML Document.

(In reply to David from comment #0) Had the same issue in Nightly for the last week and appears to be related to the settings for PDF opening. Had this set to an external reader, and it would infinitely attempt to open it without success. Setting it back to "preview in firefox" solved the issue.

I just experiment this bug and it's awful. Endless opening blank tab, even i modified the "preview in firefox" in options, or thru about:config where i re-init pdf's opening options. I try opening several pdf's docs. (Firefox 47.0 - windows 7)