I am using a Nokia BH-505 with my N900 since half a year without any problems for music listening and phone talking. Works reliable as it should. Like the fact that all the music player control buttons of the BH-505 work with the N900 Media player.
Only drawback is you can loose those tiny plastic in-ear caps easily.

Not sure if anyone mentioned this but there is a bug report: Bug 9367

I am having the sound freezing problem, etc. too with my KIA. Having to reboot to fix things every time was a real pain. After some searching, it looked like a lot of people in the android community were having similar problems when A2DP support was added. I decided to disable A2DP to see if that was the problem and it is!

So A2DP is causing sound policy problems and needs to be fixed. In the meantime, one can disable it by uncommenting and changing the "Disabled=" line in /etc/bluetooth/audio.conf to be:

Disable=Control,Source,Sink

and then reboot.

Thank you so much, you have saved the life of my N900!

Because of the CK-300 problem I was at the point where the N900 was about to be retired and I was about to move onto another phone.

Now however you have saved it for me. I can now use it with the CK-300 and not have to restart or access x-terminal to type in "sudo gainroot killall -9 pulseaudio" each time.

I love the N900 and now I dont have to kill it.

You have made my day.

my problem is i can connect to n900 so easy with sonyericsson bluetooth. i can talk and listening to music really clear. however, the phone just not transfer sound to my bluetooth after 15 or 20 mins conversation. i noticed that my music sound still transferable. but cannot talk anymore, nomater how many time i reboot and re-pair the device.

i've tried with your method above. but it already disabled at the line. but my file shown only Disable=Control,Source no sink. so i added "sink" then reboot, still not solved the prob.
any idea?
thanks

I got a BH-201, usually it works fine, but every once in a while it won't connect until after i cycle bluetooth on the N900, and while the headset is connected the N900 has issues with finding nearby devices (like for sending a calling card). Back in pr1.2 often it would not shutoff the speaker (there was a bug in pr1.2 that would keep sending "silent" sound to BT headsets), that has been fixed on pr1.3 (but now every time a sound start after a little bit of silence the headset interrupts it a few milisecs after it starts to sound it's own beep for some reason, and then it will resume the sound from the N900 if it isn't over already, quite annoying)

I sometimes get a short audio drop with my BT car radio. I am using mediabox.
After the drop the sound is running a little bit faster to get in sync again. Then
it runs normal until the next drop. The drops appear every few minutes. I am
using the power kernel clocked up to 850Mhz.
Any solution?

I think, it if the wlan search triggered every 5 mins on my device.