Its a Spam but searching message boards looking for links to other sites. Once it finds a site with open registration it may try to register and then post spam on your board once. If it gets a post it may then try to spam the crap outta your board.
I have seen this activity in other forums all over and they are usually from China. The funny thing is that they usually use a proxy of some sort.
It most likely found this site by way of the UBB.Threads link at the bottom of someone's board in the "Powered by" copyright.
