PayPal New API - IPN from SandBox on Prod configured site

[wjr]

Hi,
I have managed to configure VM 1.1.8 & 1.1.9 with a PayPal new api as the only payment method. All transactions work smoothly from a customers perspective, the transactions complete, money changes hands etc.

My remaining issue is that I get the following error from the IPN sent as an email to the website owners email address:

An Invalid PayPal Transaction requires your attention.
-----------------------------------------------------------
REMOTE IP ADDRESS: 66.211.170.66
REMOTE HOST NAME:
Order ID: 8
User ID: 64
Response from www.sandbox.paypal.com: HTTP/1.1 200 OK
Date: Mon, 27 Jun 2011 02:56:50 GMT
Server: Apache
Set-Cookie: c9MWDuvPtT9GIMyPc3jwol1VSlO=D_kv-xNzkdeq8JlK64P-slXTyiFxzJ6ZTWu7PYdeVFKj_7nkx-jgSdRo72bK9rueJeJ5MhkpuVDKCSvQut0RPNUY43BgKR3X5swL7UKOumPgZOD6U1tepeCl63q6O95ADtyalW%7cNGE7LGOfEWXdAhuPVD475qebAjmoK4326IjUvxzaiPW0o7BSpmIOIo8MtIhZikYTDCI1EW%7c2vFbpGW1ZXFJ_3L6U1X5bTuZOnn0X8p5ERaNok15zc0JfhvJqAiBkvfNJehx1lqtSuiXmG%7c1309143411; domain=.paypal.com; path=/; HttpOnly
Set-Cookie: cookie_check=yes; expires=Thu, 24-Jun-2021 02:56:51 GMT; domain=.paypal.com; path=/; HttpOnly
Set-Cookie: navcmd=_notify-validate; domain=.paypal.com; path=/; HttpOnly
Set-Cookie: navlns=0.0; expires=Sun, 22-Jun-2031 02:56:51 GMT; domain=.paypal.com; path=/; HttpOnly
Set-Cookie: Apache=10.72.109.11.1309143410776910; path=/; expires=Wed, 19-Jun-41 02:56:50 GMT
Connection: close
Content-Type: text/html; charset=UTF-8

INVALID


Note that it comes from sandbox.paypal.com, which should not be involved in the transaction. The production PayPal account (which is the one configured in the PayPal new API config) sees the correct transaction, so it must be configured correctly.
I have searched and searched this forum, and others but haven't come across anything similar. Does anyone know why I would be getting this?

Thanks in advance.

[Silentone]

Also getting this, any fix?