Please install WMP 12 (Latest one), Abobe Flash Player (Latest one). Reinstall plugin after successfully uninstalling. Edit plugin setting. Please check if all your plugins are up-to-date. To do this, go to the Mozilla Plugin Check site.

Thank you for your reply. WMP 12 is current (12.0.7601.18150), all plugins and extensions are current (Java/JDK/Flash/Shockwave/Acrobat/Google Earth/Quicktime/Silverlight/).

See image.

I tried uninstalling and reinstalling Flash plugin - no change.

What do you mean by "edit plugin setting"?

My main question is:

Can other people get mp3 gmail attachments to play in Firefox 31 without downloading them? If so, how?

Thanks...

I also tried restarting Firefox with all add-ons disabled, and having Firefox create new, clean prefs.js, and neither solved the problem.

Images show my installed plugins and extensions.

The mp3 will play in Firefox if I choose to open the file in "Music Player for Google Drive."

The problem occurs on three different user accounts on 2 different Win7 x64 systems. Looks like a Google problem.

This is absolutely a Firefox problem. I tried the suggested toggle and nothing resolved. I downgraded to Firefox V30 and the mp3 player in Gmail works perfectly.

Mozilla, please get busy and fix your browser. The upgrades are forced on me and then it doesn't work on key websites. I'm fighting to stay off IE and Chrome but you don't make it very easy to remain a loyal customer.