To Outline or Not To Outline

From what I've read, there are two kinds of writers: those who outline (outliners) and those who don't (seat-of-the-panters). I'm an outliner. I've tried writing without one, but my work tends to drift off in strange directions, then I've got to delete a ton of it, get back on track, and waste lots of writing hours going nowhere. So I've learned my lesson. I think through the story, get the basic direction written down, then dive in.

I have a feeling I've gone off the deep end this time. My newest work-in-progress is so thoroughly outlined, it's almost kind of boring when I sit down to write it out dramatically. There are no surprises--at least, there aren't at this point, and I'm 12,000 words into it. Yeah, it comes out really fast, but there's no mystery here. I don't find myself surprised by a turn of events, or thrilled when a character does something unpredictable and fun. I know I'm in charge of all these things, so there really shouldn't be any mystery or surprise or thrill... and yet, I remember, in other works, when something unexpected showed up and knocked the socks--er, flippers--off my feet. I kind of miss those moments.
How about you, fellow writers? Have you ever over-outlined and sucked all the joy out of the writing? If so, how'd you get the magic back without sacrificing the entire work?

-Sonja