[Plugin: Contact Form 7] contact 7 – not submitting, wheel spinning – windows

I have contact 7 working fine on a Linux server but when I restore the entire site to a windows server the form will not submit (the rest of the site is fine). It does not seem to get past validation to actually sending. I did test email flow and email is fine from other modules via smtp so I do not see that as a problem (using “Configure SMTP”)

when I submit a form with required fields blank it does not give me validation error, just spinning wheel and it does not time out. Same issue when all required fields are filling in. That is why I do not think this is even a sending issue.

I tried uninstalling and re-installing, same problem. Server is win 2003 IIS

http://wordpress.org/extend/plugins/contact-form-7/