Since just before 2.2 was released I have been suffering serious cell signal degradation. In places where I used to receive full signal and 3g I now sometimes lose all signal.

Processes I've followed to try and fix:

*#*#4636#*#* - Have changed radio band from Euro to Automatic to Euro again

*#*#4636#*#* - Have changed from WCDMA preferred to GSM Only - sometimes it makes a difference and sometimes it switches back to WCDMA automatically

Settings > Wireless & Networks > Mobile Networks - Use 2G networks only - this doesn't help - incidentally sometimes the phone switches to 2G only automatically and then when I check *#*#4636#*#* again the WCDMA preferred is back again and it won't revert to GSM only

Settings > Wireless & Networks > Mobile Networks - have selected Vodafone UK as the service provider and then selected automatic - doesn't seem to make a difference

Settings > Wireless & Networks > Mobile Networks - sometimes I can see every other network in the area except for mine (Vodafone) - even those that would be considered weaker than mine

Sim card - if I put my Sim card in my wife's Nexus One it works fine everywhere, on the flip-side when I put my wife's sim card (O2) in my Nexus One it doesn't pick up a signal - same way mine doesn't pick up a signal

The issue is localised to the phone, I'm certain of it but I believe it's not H/W - and here is the reason why:

Last week I was using Google Navigate to go to Dublin in the Republic of Ireland - because I was roaming when I left Northern Ireland in the UK I had to allow data when roaming to ensure I didn't lose my way. When I had crossed the border and enabled the data connection while roaming the phone sprang into life and I was all of a sudden getting full bars of signal consistently and 3g throughout the day. I checked About Phone > Status and my signal strength was like -51dbm whereas over the last couple of months it hovers around -100dbm. The phone had somehow fixed itself. A couple of days before I had done a factory reset - I hadn't reinstalled all my apps so that evening I reinstalled some including skyfire browser. As soon as I installed skyfire browser the signal dropped and hasn't come back properly since. I have done factory restores again and of course uninstalled skyfire browser but I now fear that the skyfire browser somehow ruins the radio firmware or phone firmware.

And that's why I believe this is firmware/software related - can anyone help me as I now think that sending to HTC isn't going to make a difference?

Please help!