I registered a domain in 1999 called The[word1][word2][word3].com. In 2009 a company registered a trademark of [word1] [word2] [word3]. He now is threatening me with trademark infringement. His company didn't even exist until 2004 when they took the .net version of my domain.
In 2000 I registered [word1][word2][word3].com as well to avoid issues of people forgetting to put the word THE at the beginning. I have done this sort of thing with many of the domains I own and operate to guarantee I don't have people grab a domain that could be confused with mine.
Do they even have a leg to stand on? I was first to use the term in commerce. How can I stop this before it starts to cost a lot of money?