Great hack, but i had to uninstall it, there is a huge error!!
When someone registered to my forums, he got an error a huge headers error, (you know, that headers have already been sent bla bla bla) and in the top of the screen there was something about class_dm_user.php, and it gave an error, said that strpos has an empty delimeter, and said the error is on line two thousand and something, i went there and it was a hook call for private_insertpm_process, so the plugin in private_insertpm_process has an error in it. i think it clashes with the fact that my forums sent a PM to new registered users. I'm looking forward to a fix, because other than that your hack works great