“Forbidden. Please enable JavaScript”

A few different users have reported a strange error appearing when they try to submit a form. It’s been appearing no matter the operating system or browser, but I haven’t personally had it happen. I got them to send me a screenshot of it, and one of them is a software developer and told me how they’ve tried a whole bunch of different computers and operating systems, but the error still appears. No idea why it’s not showing up for me, other than I’m the admin.

The sequence of events is as follows.

1. They fill out the form.
2. They hit “submit.”
3. The error “***Forbidden. Please enable JavaScript.***” appears under the “name” field, which is the first field in the form.
4. If they hit “submit” again, it works, and I get their request.

Unfortunately, people are turning back when they get the error and don’t resubmit the form, so I’m losing business.

Any advice you could give and/or fixes you’ve got would be appreciated.

The page I need help with: [log in to see the link]