Why can't I rotate a text box?

When I go into Format Text Box / Size, I see a
rotation option. But it is greyed out -- unusable.

That suggests to me that something -- some other
option -- is causing the rotation option to be
inapplicable.

I have gone through all of the Tools options.
I have disabled nearly all of the automatic
corrections etc, to no avail.

I can use Text Direction. But that limits me
to multiples of 90 degress. I was hoping to
turn text 45 degrees -- and ideally to any angle.

Can I do that?

I am using MS Word 2003 (11.6359.6360) SP1 on
an MS Win XP Pro system.