My Sony Ericsson W900i was working fine until I went and used Sony Ericsson's Update Service. Immediately after the update, which went through without a hitch, the phone function went dead. Tried a number of times using 4 different computers and the phone function remained dead. Checked with Sony Ericsson's hotline and was asked if I have read the disclaimer. Checked with the service center and was told I have to pay just for them to determine if it was their software giving problems. Wrote emails and received no helpful replies. Finally gave it up and got a Nokia N95 8G instead.
Warning to all Sony Ericsson cellphone users - use Sony Ericsson's update service at your own risk. Also, a new Sony Ericsson phone I got for my daughter (before my w900i problem came about) could not save appointments from day one. Did not bother to get it fixed since it will require going to the service center, queue up for over one hour, leave the phone with them for a few days, then queue another one hour when collecting. Too much hassle facing unfriendly customer service staff.