Try uninstalling one of your adobe flashes you have 11.5 and 10.3 which will always conflict.

Thank you, but it didn't work - I did uninstall Adobe Flash, then tried to install version 10 something, but it automatically went to install v.11.

     Maybe the problem is with the YouSendIt add-in?

Recent crashes of certain multimedia contents (this includes Youtube videos, certain flash games and other applications) in conjunction with Firefox are most probably caused by a recent Flash update and/or a malfunctioning browser plugin such as Real Player.

In order to remedy the problem, please perform the steps mentioned in these Knowledge Base articles:

• Flash Plugin - Keep it up to date and troubleshoot problems

Other, more technical information about these issues can be found under these Links:

• http://forums.adobe.com/thread/1018071?tstart=0

• http://blogs.adobe.com/asset/2012/06/inside-flash-player-protected-mode-for-firefox.html

Please tell us if this helped!

I uninstalled Flash and reinstalled again - same procedure as yesterday but this time it worked. I tested it by beginning to send myself a large file via YouSendIt - it worked! Thank you Much,