[TomGuy]

FF has had problems with Adobe Flash and PDF for a while.

You might try the add-on, PDF Download. I use it, but I stopped upgrading Firefox at ver 15 and stopped upgrading Flash about the same time.

http://www.pdfdownload.org/

It has gotten to the point with Win 7 that any type of upgrade creates more problems that it resolves. Win7 upgrades cause glitches. Java upgrade causes new problems. Firefox updates conflict with add-ons and plug-ins.

It is gotten to the point that the upgrades, even for ‘security’ purposes, are worse than what they are trying to correct.

[oh8eleven]

It has gotten to the point with Win 7 that any type of upgrade creates more problems that it resolves.
Bought a new Dell PC w/ Win 7-Pro about six months ago. Have updated OS and all software every so often - zero problems.
Your results may vary.