There is an additional (cosmetic) change required:-
In components/com_comprofiler/plugin/language/default_language/default_language.php, at line 998 change[code:1]DEFINE('_UE_VALID_UNAME','Please enter a valid username. No spaces, at least 3 characters and contain 0-9,a-z,A-Z');[/code:1]to[code:1]DEFINE('_UE_VALID_UNAME','Please enter a valid username. No spaces, at least 2 characters and contain 0-9,a-z,A-Z');[/code:1]I'm afraid I have to mark CB down for not using a single parameter here. I hope this is fixed in a forthcoming version.