Thank you Kevin,
I tried and it didn't work.
I then read online that Adobe software needs all the languages from the OS, and it turns out that, a couple of days before, I got rid of chinese, japonese and other languages so that I could get more free space (with monolingual).
I re-installed leopard, but still didn't work - so now I formated the computer and everything's fine.
And I'm never using monolingual again...