VR Zone reports Adob's Flash 11.3 plugin is causing issues with crashes or no contents loading in Firefox. Mozilla and Adobe have not been able to resolve the issue, but so far one of the only solutions for those experiencing problems is to downgrade to a previous version of Flash.
Firefox browsers that are currently running on Windows 7 and Vista that experiences crashes/or no contents on flash media sites should downgrade to Adobe’s previous version of flash. This, of course, will only be temporary as Mozilla announced that they are working closely with Adobe to “diagnose and address these issues.”
Approximately a quarter of the world’s internet browsing are done with Firefox, and many multimedia sites utilize Adobe’s Flash technology. So it's safe to say the Adobe-Firefox Flash issues will be fixed soon.