1054 Unknown column 'p.products_id' in 'on clause

If you have Zen Cart 1.2.x with Ultimate SEO contribution running on MySQL 5.0.x, you will probably very soon run into the following error, preventing even your front page from opening:

1054 Unknown column 'p.products_id' in 'on clause'

This is a bug of Ultimate SEO contribution. To fix it you will need to replace two occurrences of the following two lines:

FROM ".TABLE_CATEGORIES." c, ".TABLE_CATEGORIES_DESCRIPTION." cd

in includes/classes/seo.url.php with these lines:

FROM ".TABLE_CATEGORIES_DESCRIPTION." cd, ".TABLE_CATEGORIES." c 

as pointed out in this post on Zen Cart forum.