Double computer name on network and NAT issue with Back to My Mac

These are the problems I am having:
When my MacPro workstation (which on the network is named "The Beast") wakes from sleep - I get a message saying "there is already a computer on the network with the name "The Beast". Other computers on the network can now find you at "The Beast-2"" and it gives me a new name in the file sharing preferences - even though it is the only computer on the network with that name.
Why is this happening???
The other problem is with BackTo My Mac - When I try to enable it - I get an error message saying "Turn off NAT Addressing" - which I thought was turned off since the AEBS is in Bridge Mode. Why is this happening?
Here is my network setup which consists of the Modem / Router from my ISP - an Airport Extreme Base Station and one Airport Express - which is connected to my MacPro via ethernet. The MacPro does not have an airport card installed and is running OSX 10.6.8 - all other computers / devices are running 10.7.x and iOS6).
VDSL Modem / Router (from Internet provider) with wireless turned off - (so it is not broadcasting a competing wireless signal) - connected via ethernet to my Airport Extreme Base Station.
Here are all the settings on the AEBS and the Airport Express: - I am using Airport Utility 5.6.1 on my Mac Pro running OSX 10.6.8 - so the setup prefs are different than the newer version of Airport Utility found on 10.7.x systems - but both work fine. Although I did notice that the option to allow ethernet clients to connect to the Airport Express does not exist (or I just didn't find it) in the newer version of Airport Utility.
Airport Extreme Base Station is set up as follows:
Wireless Mode: Create a Wireless Network
Wireless Settings:
Allow this network to be extended IS CHECKED
Radio Mode: 802.11n (b and g compatible)
Wireless Security: WPA/WPA2 Personal
Access Control:
MAC Address Access Control: Not Enabled
Internet Settings:
Internet Connection:
Connect Using: Ethernet
Connection Sharing: OFF (Bridge Mode).
Configure IPv4: Using DHCP
Advanced Settings:
Logging & Statistics:
Syslog Destination Address is blank (as in nothing appears in this field).
Syslog Level: 5 - Notice
Back to my Mac is turned off - but if I try to turn it on I get an error message saying "Turn off NAT Addressing - which I thought was turned off since the AEBS is in Bridge Mode. Why is this happening?
IPv6 Mode: Link-local only
As stated - my MacPro with no wifi card -  is connected via ethernet to an Airport Express which connects wirelessly to the AEBS for network and internet access.
Airport Express Settings:
Airport Settings:
Wireless Mode: Join a Wireless Network
Allow Ethernet Clients IS CHECKED
Wireless Security WPA/WPA2 Personal
Internet Settings: Are grayed out (as in I can't change these settings - I assume because they are being controlled by the AEBS) and read as follows:
Connect Using: Wireless Network
Connection Sharing: OFF (Bridge Mode)
Configure IPv4: using DHCP
All other settings are identical to the AEBS.
All other WiFi devices in the house (MacBook Pro, iPhones, iPad's, iMac, Apple TV, Nintendo Wii etc…all are able to connect to the network and connect to the internet - no problem.
Thanks for any insights into what might be causing the double name on the network and why it is asking me to turn off NAT addressing - when both my Airport devices are in Bridge Mode?


I am also having this issue... any updates on this??