Guys, I still have this problem (see my post #11). It is now very frequent, happens almost all the time. I have tried to improve the contact of the SIM card and the card holder inside its tray by adding some tape and a pice of paper. But I believe the problem lies somewhere else. This complete loss of connection happens both in 3G and in WLAN mode, but only the 3G connection gets lost. It completeley loses the reception (no bars on the display), then a minute later it asks for the PIN. Once I enter the PIN, the GSM connection comes back. But then very soon again the same problem happens again.

Any ideas anybody?