I set up a Zen-cart site that's been working fine for a couple of years. But recently getting this error:

1054 Unknown column 'p.products_id' in 'on_clause'

on catalog pages.

Nothing's changed except probably PHP/MySQL upgrades on the server.

Any clues to this error?

Versions of the systems installed are:
Zen-cart 1.2.4.1
PHP 4.4.7
MySQL 5.0.24