Sometimes proxy servers screw up and cache POST forms. This is mainly a problem from forms that are identical, such as popular items being placed in the basket and then the user pushing the checkout button.
Set TolerateGet to Yes to allow
GET forms. You will be able to use
METHOD=GET on the form if necessary, subject to the normal limits of query string length. You will want to set the variable
mv_session_id to ensure that the session is not lost on browsers that don't support
cookies:
<INPUT TYPE=hidden NAME=mv_session_id VALUE="[data session id]">
It would be typical to employ this on your shopping cart page or perhaps put it on the interact page that is shown when the normal error is received.
TolerateGet Yes