I have installed Contact Form 7 on two domains. On the one domain it works fine but on the other, it does not. On the non-working domain and after installation, the page does not open after clicking on the "Contact" or "Edit" buttons on the left menu bar i.e. a blank white page is displayed (in Firefox) or in Internet Explorer an HTTP 500 Internal Server Error saying the website cannot display the page.
Has anybody seen this before or have any suggestions how to get Contact Form 7 working?