yes, I have this problem with my 8700c phone connected to my Prius handsfree. I've tried Motorola phones connected to my Prius and it does not have the problem. I've tried a second 8700c and it has the same problem. It's really back how it disconnects every 30 seconds. It also happens in bursts, meaning that it will do it all the time and then sometimes it does not do it at all. I'm convinced that it's a problem with Blackberry and it's very bad that no one response a solution or some firmware upgrade to fix this. I'm considering upgrading to the curve just to see if this problem goes away, but I since I've not heard from Blackberry about the issue, I'm concerned that their customer service is not worth staying with the company and moving on to a different phone.
wishing my phone was more solid
~fern