When I enable CCK base content module I get a white screen.

PHP logs show:
PHP Fatal error: Cannot redeclare content_install() (previously declared in /var/www/web3/web/modules/cck/content.install:12) in /var/www/web3/web/sites/all/modules/cck/content.install on line 79, referer: http://www.fooo.net/?q=admin/build/modules

I feel really stupid after one hour of check and uncheck modules looking for module incompatiblity... instead of reading the error.
Seams clear to everybody that cck is installed twice: in new /sites/all/modules and in the old /modules.

Posting as closed support request, to avoid others spend hours with silly stuff.