Although my home page and some others respond,

Many of my pages now respond with
1054 Unknown column 'p.products_id' in 'on clause'
This problem is usually caused by using mysql5 with zc v1.2.x. If this problem has recently shown up after your site has been working with no problems, then the likelihood is that your Host has upgraded mysql. If that is the case then I would be complaining to my host.

Mysql5 uses a much stricter SQL interpreter and some queries in ZC v1.2.7 and earlier will fail. Fixes were introduced into ZC v1.3.x to fix this.