I installed it on my MBP and everything was great, even gained 21GBs. Went to install it on the gf's 6 week old uMBP and it totally wrecked it. It was installing for a few mins, then it rebooted and the screen went black and just stayed like that for an hour. Tried taking the disc out and installing from boot + C.. I get the apple logo and the new beachball for a min then the screen dies again. Tried installing several times now. No joy.