Here's the editor again!

sorry, I was looking for a thread about mapmaking but couldn't find it. I have a similar problem: I create a random map, go into the editor, fix all the errors, and then start saving, and I get the message: "As you've changed this map, the rmg marker will be lost, and multiplayer regeneration won't work." And then the map becomes a few kilobytes in size and can no longer be opened or loaded. What should I do? I don't understand. D:\games2\Heroes of Might and Magic V\Heroes of Might and Magic V - Tribes of the East\Maps is the path to the map. Everything is in English, so what's the problem? Please help.