My brother in law brought his soft modded box over yetserday. WHen it boots up it just goes to a black screen, no dash. So I fired up Slayers and it booted ok but I cant select any options on the screen. ANy ideas what the problem might be?

Maybe it's just the controller not working?
Have you tried a different controller port?
Maybe plugging in the controller after the xbox has booted helps?
Are you having ftp acces to the xbox when the slayers has booted?

regards.