On virtual appliances of Syslog-ng Store Box warning message appears about the BOOT firmware being TAINTED.
You may get an email alert with the subject "Notification received: XCB-SNMP-MIB::xcbFirmwareTainted"
Ensure that is indeed the cause of the warning.
Log in to the boot shell of the appliance and run the following:
xcbclient self xcb_check_boot_files
If you got this then please go ahead and apply one of the workarounds described below; if your output differs from the above then this guide is not for you; please file a support ticket and upload a debug bundle for us to analyze your situation.