Are you using a download manager or are you using the "save" option? FF4 should be able to view PDF's natively, but if not, there are add-ons to view them within the browser. Use one of those to view it rather than downloading, then use the PDF toolbar's Save icon or try the File -> Save option as possible work arounds. It should save any file though regardless of size. Have you checked disk space where the download is being saved to?

I do not receive the download manager window when opening pdf on this particular site. I went through IE and all files appear with no problem. I right click the link and get no save option. I will check out the add-ons. Otherwise, I am back to IE. Unfortunately, the university wants testing done on Firefox.

Any chance your school uses Blackboard / WebCT?
If so, Firefox 4.0 hasn't been certified as being compatible with that software.

See this Blackboard KB page to see which version of Firefox is certified for the version of Blackboard Learning System Vista or CE used at your school.
http://kb.blackboard.com/pages/viewpage.action?pageId=45581177

One of the fixes in Firefox 4.0.1 relates to a bug entitled "Adobe PDF Files Larger than 5 MB Won't Load in Browser". Maybe it's related, maybe not.

Yes, I am using Blackboard. I called tech support at the school and they told me to go back to the previous version. Thanks for your help

You're welcome.

Please click the Helpful' button next to the answer that solved your Firefox support issue, when you are logged in, so this thread gets marked as Solved to help other users who may have this same problem'.

You Fire Fox told me to download the latest greatest Adobe crap and it is even worse. Now Fire Fox will not download any pdf files. Like I have time to look through 10 million problems to find the solution to make Fire Fox download any pdf files. The internet sucks. Fire Fox sucks. The stinken computer is going out the window very soon. Look out below!

@RobHobdell, could you start your own new question? This will help by capturing a list of your plugins.

As a quick workaround, try opening PDFs outside the browser. In Adobe Reader, open

Edit > Preferences > Internet

and uncheck the box to view PDFs in the browser.

Meanwhile, I'll get my helmet.

Hello, Can you clarify where to choose the option to open pdf's in a different window? I'm having the same problem with loading larger pdf's. If I copy the address to IE, they load up right away.

If you use Adobe Reader, start Adobe Reader (outside the browser), then look for the menu item:

Edit > Preferences

On the left side of the dialog, find Internet in the long list of categories and click that. Then you can uncheck the box for view PDFs in the browser.

If you have a paid version of Acrobat, I assume the setting is in a similar place, but I haven't checked.

Note: this should affect all browsers.