Somebody has taken insurance out on my property. Is it a problem? And what should i do?

Nobody can insure your belongings but you. This does represent a problem, in that it may mean that someone intends to commit insurance fraud based on your property--which can come back to haunt you--and/or that someone else believes they own your property, which could similarly cause trouble. You should resolve this immediately. If you know who it is, tell them it's your property and they have no right to insure it--that's their chance to show any documentation they believe entitles them to the property, at which point you can try to resolve the matter. If you know who the insurere is, contact them and tell them that you are the owner and you did not authorize anyone else to insure; demand they cancel the policy.  Again, if there's evidence that someone else has a claim on the property, it should come out then and you can try to resolve it. If it's real property you're talking about, then go to town hall and check the documentation--make sure it's only in your name.

Basically, follow up on every avenue to find out why someone else feels they can insure your belonings, and to cancel any policy you have not authorized.