I have a couple PHPBay wp sites but I cannot use the "Encrypt eBay URL's" feature. When I have it clicked ON and then click on one of my ads, it shows 404 error page not found. Turn it off and they work fine. This is the same on two different sites. Any one else have this problem?
Make sure auction.php is in your root folder. When encryption is turned on, it uses auction.php to go navigate outbound. If auction.php is missing, a 404 will occur.