well, i have just got it open. How??
well when i used to open it, i was not connected to any wifi network.
Now when i was connected to WiFi connection and disperately tried to open this new mms, it asked me to change the connection to MMS GPRS connection so that to download the cotent of the mms and this got it opened. It seems when you wanna get the message open you need to be connected to your MMS connection before.

I hope this helps