403 error during logout on Joomla 1.7.3

www.case-club.ru/index.php?option=com_comprofiler&task=logout&Itemid=140

I solved the problem. Id 140 is a menu item for guests only which allows registration ( www.case-club.ru/index.php?option=com_comprofiler&task=registers&Itemid=140 ). If i make it public logout works ok. It is done through CB menu item - registration rather than an External url with link to registration through module.
Now I made REGISTRATION menu item visible for guest only through External url menu item with link to that of CB module. It works fine now.
But why this is a case?

Good find.

This means this step of CB installation has not been done:

You must have one CB Profile menu which is public (that works for registered users and guests too).

This is probably because the logout itemid is computed before logout and got a different Itemid that didn't work on public access that Joomla gave 403...