I did an upgrade v 1.3.6 to v 1.3.8a on my test site (installed in a folder on my domain) (shared server) and sporadically get the following error ~ usually after accessing customers/orders in the admin panel:

select * from zen_project_version WHERE project_version_key = 'Zen-Cart Database'
After this error shows in admin, the front end also goes down.
Other databases on this hosting are not affected - my demosite, my main site, my forum are unaffected.

I do nothing other than close admin and close the frontend and wait, and eventually the store and admin are accessable again.

On a client's site (dedicated server) when this happens, all databases are affected! Forum, Testimonials (not part of zen cart) and the zen cart database.

I can provide urls and other info as needed.

Totally lost here - Doc? Ajeh?

Thanks ~ Tina