User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7) Gecko/20040626 Firefox/0.9.1 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7) Gecko/20040626 Firefox/0.9.1 When I open a PDF link in the browser, it opens and displays fine. But when I click "back" the browser hangs and needs to be killed and restarted. Reproducible: Always Steps to Reproduce: 1. Open a PDF with the browser 2. Wait for it to load 3. Click "back" Actual Results: The browser hangs. Expected Results: The browser should have gone to the page containing the link to the .pdf.

WFM Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7) Gecko/20040726 Firefox/0.9.1+

This is Adobe Reader plugin's problem. I believe it's caused by the "Allow speculative background downloading" or the "Allow fast view" preference in Adobe Reader and it doesn't properly stop when you Back out of a PDF file before it's finished, causing Firefox to hang.

I don't think its an issue with Adobe. I am using Firefox 0.92 and this problem occurs on each and every instance a PDF is loaded in the firefox browser. Not only you can't back out, you can't even close the browser window. You have to kill the process.

*** This bug has been marked as a duplicate of 252048 ***