Just thought i would add to this having had a couple of trademark issues myself to deal with. Its a very complex issue.
1. It may surprise some to know that a similar mark can co-exist in the same class. i.e "Dons Motors" a garage in "location one" has a trade mark set up as "Dons Motors". Meanwhile a different "Dons Motors" wants to register the same mark for his garage in "location 2". He still gets awarded the TM providing the earlier mark doesnt object or the earlier mark agrees providing the second "Dons Motors" agrees that in wording of the class that "the mark is only applicable to location 2"
2. A similar trade mark can also exist if its in a different class or relates to a different trade business. "Dons Motors 1" sells cars whilst "Dons Motors 2" repairs motorcycles. No conflict.
3. Also, a trade mark can sometimes be "assumed" even if its not been registered at all."Dons motors" 1, had been established in location 1 for 5 years before "Dons Motors" 2 secured a trade mark not knowing about the business in another town
Where the problems comes about is from passing off. ie another company is using your TM name for a similar product/service, trading off your good name. This is where its gets involved and has to be proved:-
The first part, "who registered the mark first?" If it was assumed but not registered, "wheres the proof of its earlier existance where it was used?"
The second part is "How similar is the mark being used in relation to the official TM already registered?"
The final part and most important part is " How similar is the trade using the mark to my trade?"
Obviously, in these matters one should take legal advice but imo for what its worth the biggest problem the OP has is that the mark was already used for a domain prior to his registration of his Trade mark.
The fact that it was parked (no matter how anoying it may be to the OP) is not relevent. The domain pre existed in this trading state prior to the OPs company.
If the domain parker starts trading off the OPs established position then thats different but it looks like the OPs position would be weak as a result of the pre-existance - Thats my two pennys worth anyway.
In this situation it would be better to try and come to an arrangement with the other owner if you can. If you cant and you go the legal route it could get expensive and you have no guarantee that you would win
Hope this helps