Local name changes every 10 - 20 minutes

I have just bought a new MacBook Pro after my previous one died ( mother card seem to had been the problem). In this one like in my previous the computer's local hostname keeps telling me that the "MacBookPro-BC-617.local" is already in use on this network and changes the name of my MacBookPro-BC to 658.local.

This takes place every day and almost every 10 - 20 minutes. I'm using Mountain Lion. What could be causing this and how could I get rid of it?

This happened to me at work when we were using individual wireless access points, each acting as a DHCP server: the MBP was, at different times, catching its signal from these different access points, depending on the location and the strength of the various signals. We changed to use a central DHCP server, and set the access points to extend an existing network, and it solved this problem, as well as a similar issue where the user would get messages that the IP address was already in use.