Firefox 19 comes with a new PDF viewer add-on called PDF.js; it is absolutely terrible! The first PDF I tried to display (http://helpx.adobe.com/pdf/adobe_reader_reference.pdf) looks like this
Image may be NSFW.
Clik here to view.
To fix this and use the Adobe Reader plugin: Tools | Options | tab Applications
change (Portable Document Format)
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to
Image may be NSFW.
Clik here to view.
Now the PDF document displays correctly in the Adobe Reader plugin
Image may be NSFW.
Clik here to view.
In case you do not see 'Portable Document Format' under the Applications tab, you may need to reset your Firefox profile (Help | Troubleshooting | Reset Firefox).
