The domain name I own is www.freecraftdownloads.com .... earlier today after being on a secure site I mistakenly visited https://www.freecraftdownloads.com which resolves to someone oses website.

I've tried the same error with other domain names but they don't do the same thing... have asked other people to check in case it was something on my comp but they get the same... how do I find out whats going on and stop it? Any help would be appreciated.

OK forget I asked :-) After a bit more investigation have found out that the other site is on the same shared server as mine... have contacted my hosting company to resolve the issue.

Check with your hosting company. That other site is using the same hosting company you are and I'm guessing their site is on the same server. I don't think it's anything you did and I don't think someone is trying to get away with something underhanded, though it is a possibility.

I think this might just be a misconfigured file on the server that your hosting company can fix easily enough.

Let your web host know about the problem first and see if they can fix things.

Edit: Looks like you posted while I was looking into things, but we both came to the same conclusion.

Thanks for takling the time to look... they have no refered it to their "billing department" which seems strange to me... I would have though a server miss-config !

After a bit more investigation have found out that the other site is on the same shared server as mine

As it would be.
It should actually be part of YOUR hosting.

it will be a error in the setup and https: site will be pointed to the wrong physical space on the server.

Probably a incomplete apache setup.
When a virtual host is not defined in the Apache virtual hosts list, it shows the default (usually the first declared) virtual host of his list.

Probably that's what hapenned to you.