I doubt the brightness of the CP is the cubemap's fault - the lights in that room look to be turned up very high. Try turning them down and putting another, dimmer light in the centre of the room to balance things out. I've never had this problem, though, so it could be cubemaps. Does it still occur if you delete all the cubemaps? Alternatively, check they're all several hundred HU apart. Good luck
Edit: Also, don't put the version number in the title because you'll have to pester an admit to edit it or start a new thread every time you release a new version. Better to just leave the title as "Milkyway"
Edit edit: done