I've had a fiddle with paypal and zencart settings myself to no avail except now when the order completes it goes to a blank page.

I have deducted that it might be .htaccess as on the wikipage trouble shoot as paypal get's payment and information but zen cart doesn't think it's had an order, unless I use postal orders, so my theory is paypal can't 'talk' back to zen cart. In my searching I've seen it mentioned that it's because of .htaccess.
Thing is...how the hell do I turn it off to see if it's the problem?