Thank you guys for your responses, all of them were helpful.
I do not want to bother you nor the forum because this thread belongs to Sensation not to Desire,
but given that the synthoms are similar to both models, and acknowledging your patience, I will clarify some facts only "for the record" for all of those who are having/will have similar trouble (hope not).
at zmfl:
The problem is more like this
http://www.youtube.com/watch?v=xlNArVn7otA , except that I can not unlock the phone because the phone does not even recognize any touch.
The phone is not rooted, uses original parts (battery, memory, etc), not dropped, never get wet, bought in december last year.
After a randomly period of time, the touch screen starts working normally, responding fast to all touches -even multi-touch- in all the screen surface as if nothing had happened, and suddenly the screen back againg does not response to any touch.
I have tried what you suggest, touching sim/memory card slot area, and the screen starts recognizing touches... for a while and then back again. Also the problem usually disappear when I remove the battery for a night or more.
I guess it is the same problem that Sensation's: "some extra charge is not getting the ground", but I am not sure.
at tinky1:
The htc desire forum in
http://xdaforums.com has various post like this one
http://xdaforums.com/showthread.php?t=895625&highlight=touch+screen.
I have already done factory reset and sometimes the problem disappear... and then backup again.
I have read that the htc support people is aware of this as "the screen issue" and offer you a replacement for another phone.
The problem is that these days I am working far away from an authorized support center to get a replacement.
I agree with you that something is wrong, buy it is so wierd and random that it is hard for me to find a pattern of behaviour about the problem.
at claud_face:
I have not run through your situation. I would recommend you to go to authorized service.
I will keep searching. Whatever I find, I would post it.
Thank you very much for your time. The community spirit is powerful.