I have a Civic with hands free and am experiencing a similar issue with my 3Gs.
If I leave bluetooth enabled on the phone all the time, when I get in the car the phone will sync and then the connection will drop out. If I then try and use the phone, it is very sluggish and trying to turn bluetooth off often doesn't work. It will eventually say that BT is off, but if I check a minute or so later, it is actually still on. Trying to turn it off again seems to work. Sometimes the phone needs a reboot though.
If I only enable bluetooth each time I get in the car it seems to behave better. Problem is, I usually forget to turn it on 😟 Too used to my K750, which was flawless in this respect.
Wondering if I should ask for a replacement...
W.