I have to report a similar issue.

What I have noticed is that if the device you are pairing with advertises A2DP as well as handsfree, like HFP, then you have issues. If just using it for handsfree, HFP or HSP and not flipping back and forth from A2DP.

Reason I have conclude this I had a stereo in my car, cheap Aldi one, that only did handsfree and had no issues.

I have replaced it with a stereo that does handsfree (HFP) and streaming (A2DP) and I am getting issues like above.

I am suspecting the N900 more than the Clarion car stereo.

Is there a bug I can vote for??