Realplayer downloads no longer functioning properly

Hello,
Can someone please help with the following problems:
I am having a problem playing realplayer videos that previously functioned. The videos now
1. Either hang up and never play or
2. Play after a long wait.

These are videos that previously played with no problem.
This problem is occuring on a Windows 7 machine.
I am using the latest version of realplayer and firefox.


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Also before this problem started the downloader button stopped appearing when I used firefox
using windows 7. Oddly I have another machine with the same version of firefox, Realplayer but using xp and the download button appears. It seems to be a problem with Windows 7. The download button always appears with internet explorer. The download problem only seems to be a problem with the combination of Windows 7 firefox and realplayer.
Thank you in advance for any information.