I printed out these hands with my Makerbot 2, and it seemed that the print skipped layers and added support instead. This doesn't seem like an extruder problem. It's happened to my last 4 prints.

I'll put these photographs so it can explain itself. You can see in the side picture, that the curve on the hand is fine, and that its leaving the layers empty with support.
http://www.mediafire.com/view/l3pzbh...i/IMG_0912.JPG

http://www.mediafire.com/view/j3hv5h...5/IMG_0913.JPG

I'm wasn't sure where I should post this, I found this site.