We were trying BoT 25 man last night with mostly the same people we do 10 man with but it was mopping the floor with us. For one thing we lost a tank quick which was never actually me so I don't know for sure what happened.
Does any of that trash have an ability that this fixate bug would mess with? That was my first 25 man raid ever and frankly if they are that much harder than 10 mans I choose to pass and thank god nothing requires 25 man.
Top Hotfix & Bug listing here
http://www.mmo-champion.com/content/