I have logged this with tech support, but wanted it on the forum so others might find it useful.
This is quite a common setup of ours, which is repeated maybe 50 or 60 times, but in this case I have a problem. I setup a VRRP interface, the IP on that interface is to server as a redundant gateway to equipment that is connected to both Routers, and the routers themselves have a cable bridging them. When its setup, one of the routers logs "VRRP received packet with bad checksum" and they both end up being masters of the IP.
I logged it with support. Logically, they have asked to replace the cable, but in actual fact, doing a packet capture reveals the checksum is bad for the packet even before it goes down the wire. I've also upgraded at their request, no luck yet.