I just discovered that the Subscribe2 widget (and perhaps any other form-based content) fails in Internet Explorer if WP Super Cache is enabled. If I half-enable it (cache only, no super), it works fine, but if I enable it, and the page I'm on is super-cached, attempting to subscribe to the site's newsletter results in this error:
Method Not Allowed
The requested method POST is not allowed for the URL /wp-content/cache/supercache/www.harriswholehealth.com/about/index.html.
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Apache/1.3.37 Server at www.harriswholehealth.com Port 80
Oddly, in Firefox, it works just fine, even though this is a server-side error. Is there a fix for this, or must I simply keep WP Super Cache in "half on" status? And is this problem unique to Subscribe2, or will it choke on any form input?