False positive Internet uplink is down emails

Hello,

I'm running the free version 8.300 and I'm getting several emails daily reporting my Internet uplink is down. I know these are false positives because I have received these emails while on a VoIP call and don't loose the connection.

My ISP is Time Warner Cable and I have a Motorola SurfBoard SBG6580 modem. My uplink interface is a Broadcom Corporation NetXtreme BCM5751 Gigabit Ethernet PCI Express NIC.

What is the trigger mechanism for determining that the uplink is down and what steps can I take to eliminate them?

Thanks,
Ron