Create new user brings blank screen

Hi.
Using user_types module together with content_profile module comes to blank screen when creating a new user (of any type - either unassigned one or of added roles).
Sometimes this comes up with the "add user" form, but the error message displays "the user already exists", sometimes shows blank screen (despite php_ini is set to display errors and the errors are being displayed if any other PHP error occurs. PHP memory limit was increased to 600M with no change in this behaviour). DB log displays nothing as well.

My assumption is that there's a contradiction between content_profile module (which has -1 weight in system table) and user_types module (which has weight 1 in system table) - as content_profile initiates (triggers) creation of a new user and when it comes to user_types module - the user already exists in the system (yes - new user with all the fields exists despite blank screen or error message).

I can't guarantee I am 100% right, but it seems to me that this is why blank screen/error message comes up.

Is there any solution around it? What can be done to determine the error?