This happened sometime over the past 8 days. I can no longer get to my main page with my online catalog. Instead, I see this message:

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

Was my site tampered with? Everything has been fine on my site since I launched it over a year and a half ago.

Has anyone had experience with this error message before, and can anyone offer me a tip on how to fix it?

I haven't made any changes to the site for nearly a year. I'm using an older version of Zen-Cart. I'm not sure how to determine which version it is. I don't see anything on the Admin page that indicates which version I'm using.