No, I don't know anything about the last 10 pms hack. I don't have any sort of hack like that on my site. And do you know how many mods there are here? A lot.
This would be the forum to ask, however the response you will usually get is to Use the Search Bar. There are probably several PM type modifications and only you would know which is the one you installed.
And I didn't say start a thread in those forums - I said SEARCH in those forums. Those are the forums where the mod would be found, so that is where you should go look for it.