Hi...when im in the game i click battle.net and the patch starts to download, but when i click restart after it doenst actually restarts. but goes in windows and thats all... Do you know how i can fix this?

are you sure you got a legal copy of wc3? sounds like you cracked it.

I have another problem, it says:
My MeltingValley.w3x' checksum doesn't match. I haven't changed anything and could play with in in Battle.net...

chervilo, you need to write this game in the registry. you can download some software to do this. for example war3regfixer from war3.replays.net. it has chinese interface so this are the steps using this program:
1. Click right button: "???????(F)"

2. Select path to wc3 folder 3. Click Left button 4. In the end click "?????(S)"

Just re-install the game and everything will be fine.