Link local showing dadfailed

[msroest]

Hey Everyone,
   Just wondering if anyone can give me a hand with a weird issue I'm seeing with my ubuntu natty machine.

My tunnel is working great but there is something strange on my interface my link local address is showing the following on a ip addr

inet6 fe80::20e:cff:fedc:cf90/64 scope link tentative dadfailed
       valid_lft forever preferred_lft forever

the dadfailed is the strange thing I've checked all the other machines on the segment and there is no duplicate addresses.

Anyone have any ideas?  I've come up pretty empty trying to google search for it.

Thanks

[jimb]

Looks like it's failing on the Link Local.  Are there any other machines, or other interfaces on the same box which have the same MAC address?  Or perhaps the interface is being presented to the IPv6 stack (or the LAN) twice or something like that?