Which solutions here did you try, thus we do not recommend already tried ones?
And what Mac OS X version do you use?
Btw, OS X 10.8 Mountain Lion has that bug, where it takes quite a while to shut down. Mine takes also up to a minute to shut down, but I do not care, since I brush my teeth then.
As for your need to shut down, is it because you want to restart and boot into Windows?