HTC Desire HD looses phone signal

[drumbrake]

My HTC Desire HD has recently started to suddenly and randomly loose the phone signal. If I then turn the phone off and back on again it is then fine, until the next time the signal is lost. I'm in Kowloon so distance from the phone mast isn't a problem. Everything else seems to be functioning fine, although the micro sim stopped working a couple of weeks ago and has since been replaced with a new one. The annoying thing is that you don't realise you have lost the phone signal until you want to make a call, and then realise there is no signal. Anyone know what might be the problem?

[Raccon]

Poor contact between SIM and phone? Try putting a small sheet of paper between to press the SIM against the contacts.
Of course it's also possible that the phone has a fault, in which case you should talk to your dealer/provider.