This is what happened last night I clicked to shut down my computer it then went to the shut down screen and said installing service pack step 1 of 3 right in the middle of doing this after it got to step 2 of 3 the power went out Now when i turn my computer back on it wont go past some type of scan and it gets stuck on windows registry something about derived data. I am running windows vista with an intel pentium D 3.0Ghz. Can anyone help me please i am new to vista. Any and all Help is much appreciated Thanks.