Someone might have experienced this. I have an Exchange active/passive cluster. Both nodes have SP3 for Exchange and Trend Micro's ScanMail 6.1. I then installed Norton Antivirus Corporate Edition (NAVCE) 7.5 "unmanaged" client on both nodes. After that, I configured both nodes to exclude scanning of the Exchange's, IIS', and ScanMail's system files including the "Drive M" of Exchange. After I perform a manual failover, some of the Exchange cluster resources on the active node are stopping, offline, or have failed. This will also be the result if I switch it back to the previous node. To resolve this, I have to uninstall both NAVCE 7.5 and ScanMail 6.1, and then reinstall again ScanMail 6.1. How can both ScanMail 6.1 and NAVCE 7.5 work properly in an Exchange cluster environment? I need NAVCE 7.5 for file-based virus scanning.