I'm having the exact same problem! I also have a Samsung Galaxy Ace running Android 2.3.4, and i'm having problems using bluetooth, either with my notebook or my mp3 auto player.
I get bluetooth paired, mas i can't connect with other devices. I noticed that I accept to pair with other devices, but it didn't ask me the PIN code!
I look over internet and found suggestions to reset the cell phone to default settings. I don't want that, because I'll lose many applications / configs. Any other suggestions?