Joomlaxplorer is really an awesome component it almost reduces the tension of permission issues and several other things .It is really very easy to use directly form the joomla admin no headache of server .

Instead of this many times you got the error like as the title

Fatal error: Call to a member function acl_check() on a non-object in administrator/components/com_joomlaxplorer/admin.joomlaxplorer.php

the simple solution for this is just  enable the System Legacy plugin thats all ;)