Hi guardian
It is normal to get a blank page when pointing the browser to your interface.php

this script is not made to communicate with a browser ... only with OpenSim.
Did you replace the profile module (the dll file) with the new one? Or are there now maybe 2 profile dll files (the new one has now a different file name) in your opensim/bin folder?
Did you check, are there any entries in your table #__opensim_userprofile? And is there any line with values in it?
Is there maybe more information in the error_log of your Joomla webserver after you try to update a profile?
Greetz
FoTo50