Shift key doesn't work when moving objects in AI 10?

[chuckdesign]

I'm using the latest update of Adobe Illustrator 10 on Mac OS X. When I move boxes or other objects, I want to constrain the motion of my object in horizontal or vertical directions. In previous versions of AI, holding down the shift key accomplished this effect. But in this version, it does not work -- the object floats all over the place even when I hold the shift key.

Is there a new way to constrain motion in AI 10? Or is this another of Adobe's "undocumented features"?

Thanks,

-- Chuckdesign