I'm running Zen 1.3.8a and PayPal Express Checkout. I have "PayPal Express Checkout" installed and enabled, Paypal Standard is not installed.

A customer alerted me to this and I get the same results as her through numerous tests. I cannot get the payment confirmation page to show up - I get a page not found error.

When trying with a check/ money order payment like she did I get the following URL for the page not found:
http://papergardenprojects.com/store...eckout_process

The order showed up in my site as a new order, but I did not get E-mail notification of the order. The error log stopped at ec_step1-1. When I refreshed the screen, I got a duplicate order.

When I tried paying by PayPal instead of check, when trying to confirm the order I got the page not foud error at the following URL:
http://papergardenprojects.com/store...=1&stage=final

I recieved no notification of the order in my account and no "error" emails.

Why has my site all of a sudden stopped communicating with Paypal? I have not changed anything and it worked fine late December.

Any idea where to start looking?

Help!