OK. It seems I am correct in my assumptions above. Now I have a new problem. Actually, its a problem I thought was resolved, but apparently not. If I enable more than one adapter and connect it to the switch, after about a minute or so, it stops functioning with:
Windows has stopped this device because it has reported problems. (Code 43) and then the switch detects a 10/100 connection, but this is consistent with the device powered, but in an error state or disabled.
There is no teaming or anything special set up on the i350, nor is there any LAGs set up on the switch.
Really starting to lose hair, now.
HK