Difference in functionality between versions - how to overcome?

I am doing a e-learning course, where the individual lessons are presented in Flash.

I am using Firefox 42.0 on a Windows XPSP3 pc, and the Flash version Firefox uses, is the latest , 20.0.0.235.

My problem is that the lessons do not show. I see that my browser contacts the server, that information is downloaded, but nothing shows.

I also have a Firefox extension, IE tab, which allows me to display content within Firefox using the Internet Explorer engine. The IE engine using their latest Flash version, 20.0.0.228.

When I use the IE engivne to display the pages from my e-learning site, all content is shown correctly,.

The url of the e-learniong page is 5 Tilleggsmodul but that is most likely not going to be of any help, as the site is password protected.

• Can I downgrade the Flash-player version that is used in Firefox to the one that is used within the IE-engine?
• Is it possible that a 236-version could contain the same functionality that has disappeared in the transition between 228 to 235?
• Is there any suggestion as how I might be able my good old Firefox to display my e-learning pages?

Thanks for any suggestions