This is annoying. I once did a similar thing to a netgear "managed"
switch setup in two VLANs. Experimenting, I setup a crossover cable
between the two VLANs to see how real the separation was. My theory was
that it would work like having two separate switches. I was wrong. It
took down the whole network as if I had run a crossover back into a
switch that wasn't partitioned. I don't know whether or not this is a
bug or not, but it makes me wonder just how good this netgear managed
switch is and if I should replace it with something better for my
internal DMZ purposes.