I rencently moved my clients' website to a new hosting provider, now the cb login and register stopped working????
Was on CB 1.4 then upgraded to CB 1.7.1 when I saw it not working, was working before for more than a year.
The site is running joomla 1.5.25, was on 1.5.23.
The site in question www.1kyk.co.za( Login is located in the last main menu item)
Any ideas???

Got it solved,
Turned off standard joomla sef, the login and registration worked again.
Turned the SEF back on, it breaks again.

Turned on RewriteBase / in the .htaccess, login and registration now works fine.

The site is not located directly in the root of the server

Took all night to spot that one, and only out of desperation. The joys of development....