PayPal checkout cancels transaction after entering login details

after signing in to PayPal... clicking the "continue" paypal button has the browser cancelling out of PayPal and returning to an empty shopping cart at the website.

hitting the "back" button on the web browser brings the customer back to the PayPal page to verify payment with the continue button.

and thus starts the loop

doesn't happen on all items. but this is the second instance this week.

item is Pysanky Egg Dying Workshop

at http://erieartmuseum.org/education/spring.php

This is happening due to domain switching.

it happens as a result of switching between the www address for you domain and the none www address:

http://erieartmuseum.org/

versus:
http://www.erieartmuseum.org/

each of those is a separate domain, thus a separate browsing session

if you start shoping at:
http://erieartmuseum.org/

and paypal redirect you to the pp_confirm page at:
http://www.erieartmuseum.org/

the session and cart contents no longer exist because it is a separate domain.

to fix this, you should force all traffic to use one or the other, this can be done using htaccess:
http://www.htaccessbasics.com/force-www-nonwww-domain/

thanks.

my account disappeared this morning. i had to reregister. now all my purchases are missing

you reported this in another thread, see my reply there.