Font Book not activating User Fonts

[Sogni]

I can't activate my user fonts!
See here:

http://sergio.nzdigital.com/temp/userfontsdisabled.jpg

Clicking "Enable" does nothing,
I obviously do have fonts in my user library.
What gives?

Only thing I can think of is - incompatibility with File Vault???
But I don't see that documented anywhere! And that would REALLY bite! Altho I would be able to live with it installing my fonts in the system library - but I don't like going there!

Any ideas?