Hi,
There is an issue with submitting forms in IE9.
When clicking the submit button the confirmation text does not appear.
Although the form has been sent and the notifications, the subscriber thinks that the form must still be sent so keeps clicking on the submit button.
Here is one of the forms (select tab "inschrijven"):
http://www.lichtdeboer.nl/portfolio_1/nlp-basiscursus/
Thanks!