I gave it a try. No problem. Try these;

Clear the Cache Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"
and
Remove Cookies Firefox/Tools > Options > Privacy > Cookies: "Show Cookies"

If there is still a problem, Start Firefox in Safe Mode.

Note that this can be caused by corrupted cookies or cookies that are blocked (check the permissions on the about:permissions page).

You can inspect and manage the permissions for all domains on the about:permissions page or for the domain in the currently selected tab via these steps:

• Click the "Site Identity Button" (globe/padlock) on the location bar
• Click "More Information" to open Page Info
• Go to the Permissions tab
• Tools > Page Info > Permissions

• https://support.mozilla.org/kb/how-do-i-manage-website-permissions

You can delete the permissions.sqlite file to reset all permissions.

There are other things that need your attention.

Note that your System Details List shows multiple Flash plugins.

1. Shockwave Flash 12.0 r0
2. Shockwave Flash 11.9 r900

You can find the installation path of all plugins on the about:plugins page.

• http://kb.mozillazine.org/Issues_related_to_plugins#Identifying_installed_plugins

You can check the Flash player installation folder for multiple Flash player plugins and remove all (older) version(s) of the plugin (NPSWF32) and (re)install the latest Flash player.

• (32 bit Windows) C:\Windows\System32\Macromed\Flash\
• (64 bit Windows) C:\Windows\SysWOW64\Macromed\Flash\