[Plugin: Fast Secure Contact Form] Upgrade error: The plugin does not have a valid header

Hi

I just automatically upgraded to the latest version when my WP Admin told me there was a new version of your plugin. When I upgraded I got this response:
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The plugin si-contact-form/si-contact-form.php has been deactivated due to an error: The plugin does not have a valid header.
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I went into the back end via ftp, changed the folder name in the plugins folder, then tried to install again, I again got an error. (I have now deleted this new install & put the original folder name back to si-contact-form).

When I view my contact page in a browser, I get [si-contact-form form=’1′]

Thanks

Paul