Did you just do NewRoom, or NewRoomEx? If you just did NewRoom and the player is at x coordinate 1000, when you move him to a new room (assuming that room is not scrolling), he'll be off the screen. So the viewport (what part of the room you're looking at) will also be off the screen, which I guess is black.
By the way, do you see the character on the screen?
Also, if you've done some sort of custom room transition, and not faded back in, that could do it too.
By the way, do you see the character on the screen?
Also, if you've done some sort of custom room transition, and not faded back in, that could do it too.