Did you create the mandatory CB Component menu item?
From the included readme file:
Add a new user menu item to the "User Menu" for Community Builder:
(this will be the link to the user's profile page).
For this, go to "Menus" -> "User Menu", click New, then:
- in Mambo/joomla 1.0 select "component", "Community Builder
(comprofiler)", leaving access public for the item,
give a name and save.
- in Joomla 1.5 click in internal links "Community Builder",
then "User Profile",
leave access public for the item, give a title and alias and save.
- in Joomla 1.7/2.5 go to User Menu (if sample data was installed)
or any other Menu and click "(+) Add New Menu Item", then click the
Select button next to the "Menu Item Type *" field to reveal the
"Select a Menu Item Type:" pop-up window. Select the
"User Profile (mandatory)" item in the comprofiler section.
Give it a Menu Title (example: "My CB Profile") and set the
"Access" drop-down field to "Public". Then click "Save & Close".