Banned because i changed pc

I don't know what to think about this

Zitat von Amnesia

It just means that you took your CD key on some website or on youtube so a bunch of people use the same key... So indeed someone already got banned with it.
You should just buy the game (or use a keygen to get a unique cracked key).

if you did bought it.

claim a new one at steam

I didn't buy it through steam so I'm not sure how it works.
But personally I can go to Options > Multiplayer options > Enter key code, and see my CD key here.

If so many people played with that Key, it can't be an original (bought) key, it's a cracked key. So I don't know what you did but maybe you changed your key? I don't think it's possible that steam would sell the game with a cracked key... If you've changed your key, maybe try reinstalling your game through steam.

Edit: If it works fine on your laptop, it means you have a different key there. Go to the options as I explained above and copy your key. Then go to the options on your other PC and erase the key and replace it with the one from your laptop.