I am seeing this error... only with the "Bank Transfer" payment option, not with a custom payment gateway module that is based on Paypal's module, which is working fine. And no, I'm not only seeing this in IE... we are seeing it in Safari and Firefox. What on earth is going on with this? It had disappeared last night, and I thought one of the many system updates I'd done had perhaps fixed it. However, today it is back, making me wonder whether it is an issue that appears only when the server is under load, e.g. when many sites are calling on memory resources (as CPU is 100% idle at present, but memory is mostly all allocated.) Any ideas?