I've had an unlocked HTC Desire on Three for a couple of months and it's all up-to-date - running on Froyo and updated again just this morning. Yesterday the phone dropped off Three and roamed onto Orange which isn't right because I get a full signal on Three in my house. I phoned Three last night and they said there wasn't a problem with the network in my area. The woman I spoke to suggested taking the sim card and battery out, leaving it 5 minutes and then trying it. I did this this morning and it made no difference. I also set the phone into 3G only and manually scanned for networks and it couldn't find any. I phoned again this morning and was told there is a known bug with the HTC Desire locking onto partner networks. I've been told to get the phone flashed but that sounds like a bit of a fob-off to me, especially when I can't find any reference to this problem on the internet.