Post are uncatgorized after 2.3.1 upgrade

Hello folks,

I’m trying to upgrade a local install of WP 2.2.3 to 2.3.1 : all plugins are desactivated yet I get an error during the upgrade process :

WordPress database error: [Duplicate entry ‘1’ for key 1]
INSERT INTO wp_terms (term_id, name, slug, term_group) VALUES (‘1’, ‘Blog’, ‘blog-2’, ‘1’)

WordPress database error: [Duplicate entry ‘1-category’ for key 2]
INSERT INTO wp_term_taxonomy (term_id, taxonomy, description, parent, count) VALUES (‘1’, ‘category’, ”, ‘0’, ‘466’)

WordPress database error: [Duplicate entry ‘2’ for key 1]
INSERT INTO wp_terms (term_id, name, slug, term_group) VALUES (‘2’, ‘Web/Tech’, ‘webtech-2’, ‘1’)

WordPress database error: [Duplicate entry ‘2-category’ for key 2]
INSERT INTO wp_term_taxonomy (term_id, taxonomy, description, parent, count) VALUES (‘2’, ‘category’, ”, ‘0’, ‘142’)

As a result, most of my posts end up “uncategorized” – but they were in set categories in the former WP version !

Any ideas ?

Thanks.