[TYPO3-english] Validating the security token of this form has failed

[Joydeep Bakshi]

Dear list,

I'm clueless with a typo3 running with 4.5.34 which don't allow to edit the
templates. Foe each and every modification/addition it rep[orts

Validating the security token of this form has failed. Please reload the
form and submit it again.

The .htaccess is already modified by

php_value suhosin.post.max_vars 8000
php_value suhosin.get.max_vars 8000
php_value suhosin.request.max_vars 8000
php_value max_input_vars 8000

nothing useful, though no issue to add content. Any clue from anyone ?

Thanks