SEF won't work for a specific parent category

[Florentp]

Hello there.
I have an issue with Virtuemart default SEF function.
For a specific category, every menu links don't work when SEF is activated (404 error, component not found)

For example :
I want to access to a category called "socks", child of a category "accessories".
My link is like this : index.php?option=com_virtuemart&view=category&order=DESC&virtuemart_category_id=90
With sef activated : http://beta.mywebsite.fr/accessoires/chaussettes.html  (in french)

This is really specific to the "accessories" category.
For all others products categories, it works fine!

(I'm using vm 2.0.10 adn joomla 2.5.7)

Help on this problem will be really appreciated
Thanks.

Florent