I use a 6310i for work everyday on O2 (soon to be Vodaphone ) I have never had a problem, it has to be the best ever mobile phone, I can't see how they could improve on it. It is in almost constant use between 0800 and 1700 and the battery seems to be going on forever, even after almost 2 years of my abuse.

It connects and disconnects to my Nokia Bluetooth Car Kit in the Van, which is more than can be said for my other Nokia 6230. Signal is always good, and I get to some pretty remote places now every man and his dog can get Broadband. I have never had the problem you describe. Rock Solid!

Does it do it when you are away from your home cell ???

Edit - Doh! Re-read your post, could be a cell/phone conflict of some sort. Try taking it to your local Nokia Service Centre, they may upgrade the firmware for you, I think some Carphone Warehouse's can do it too.

Cheers

Cris.