I just went into Control Panel, change Avast BPP, and found the Exchange 2003 box red X, product not installed. This is a bug. I have SBS 2003. it should have installed this automatically as MSExchange is an integrated part of SBS. After i checked the box, and the exchange shield installed, i restarted teh server, and teh errors have gone away. I still get some errors, but hopefully they are not related to this.
Thsi is a bug in BPP. It should install Exchange shield on SBS.
At the very least, dont shut down Exchange because the shield is not installed.