I just got the same problem (blocked plug-in).

And I also found the reason why I got the "blocked plug-in".
But I still can not solve it!

The reason I got the "blocked plug-in" is bacause the "flash player" is too old and then my Mac deactivates the flash player for security.
PS: My Mac says that version of flash has serious security problem. 
PS: Flash player version 10.xxx.

So I try to update the flash player.
But the installation of new version of Flash Player just can not be completed!

How come?

Is this has something to do with chrome?
PS: Chrome has different version of Flash Player installled.