Force10 vlan exclusivity?

I had a whale of a Saturday in in my COLO today trying (and failing) to complete what should have been a very simple task.  I still do not understand why this happened, or how to fix it, but here it is.

Equipment setup:

Stacked Force10 MXL switches inside an M1000e chassis with VMware ESXi 5.5 cluster on the inside backed by the Equallogis M4001x storage set.

3 Blade servers inside all running NPAR so all inernal links are tagged.

I have been running 4 vlans forever: 1.Internal networking for virtual hosts. 2.ISCSI 3.Vmotion 4.External connectivity with other hosts on outside LAN subnets.  This is fine, and dandy.  I need to set up some connectivity to the Internet now, and Have added a 5th VLAN to my stack, and tagged the ports appropriately in bring the connectivity "inside" to the VM that needs the external connection.  Simple.  Now:

VLAN 10. Is Vmotion

VLAN 20 is iSCSI

VLAN 100 is my internal LAN

VLAN 200 is external LAN subnets

VLAN 300 is Internet,

Here it comes....when I plug in the cable (VLAN300) between my Internet switch, and the MXL the Internet comes up..HOORAY!

AND....(VLAN200) is unreachable.  Now I can SSH into my M1000e, but  cannot reach it from inside the organization.

Until - I unplug the cable leading to VLAN200 and then plug it back in then...VLAN200 becomes reachable, but VLAN300 is now inaccessable. 

I tested this 9 ways to Saturday night today, and this is all I have learned.  I cannot find any logging on the MXL stack that will give me a clue as to why this is happening, nor can I explain this myself.  I have ancient HP switches that can handle this kind of connectivity, but these cutting edge interconnects from Force10 cannot?  What gives?

Is there a maxvlans setting on these things that just will not allow those two external/internal vlans to exist together? 

Anyone seen anything like this?  I plan on calling DELL support about this first thing Monday if I can't get any help here.  Thanks for any comments you leave me.