Hi Severin,

You are "using DHCP" to connect to your Network.
Basically what the message means is that your router is assigning IP address' 
to all your devices on your Network. What's happening is two devices have the 
same IP address and then things get confusing between the two.

When this happens: On the Mac that has received the message:
go to System Preferences > Network > Advanced > TCP/IP and click "Renew DHCP 
Lease"

Nothing sinister is happening.

Cheers,
Ronni

> On 3 Dec 2013, at 2:51 pm, Severin Crisp <[email protected]> wrote:
> 
> My wife just had a message come up on her laptop to say that another computer 
> on the network was using her IP address, and gave that address.  Two other 
> computers, my iMac and our iPad were active at the time.  I shut down the 
> laptop and restarted and no further message.  I have never had this before 
> and suspect nothing sinister but can someone comment please.  
> Severin Crisp
> ____________________________________________________
> 
>              Assoc Prof R Severin Crisp, FAIP, FIP, CPhys
> 15 Thomas St, Mount Clarence, Albany, 6330, Western Australia
>                   ph (08) 9842 1950 ( Int'l +61 8 9842 1950)
>                            mail to: [email protected]
> 
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