I cannot view PDF files in Firefox. There doesn't seem to be a plug-in I can download. Oftentimes, PDF links prompt a download, and I am able to view them in my PDF viewer on my computer. But most often, PDF links do not even prompt a download, nor are they viewable in my browser. Thus, I cannot view them at all in Firefox. I have to open a different browser, such as Google Chrome to view the pdf. I don't understand why no one has developed a plug-in to view PDFs in the new Firefox. How can I fix this problem? Would you recommend I install an earlier version of Firefox to fix this problem? Please help. Thank you.