Hi Hal,
Shoot, the support forum did not email me that you replied so just seeing this, sorry.
I have all plugins disabled except yours on this dev link:
http://poetics.me/dev
You can see the Mailchimp news submit form and Contact form is showing errors. On my main public site where the Testimonials Rotator plugin is disabled, both working ok:
http://www.poetics.me
So it seems there must be a conflict between my theme and your plugin. A friend said sometimes the order of loading can create issues, but I'm not that technical in this area.
My app launches Tuesday morning, would love input meanwhile in case you're available.
Thanks,
Seth