I bought a Desire S smartphone a little more than 2 months ago, but did not have a chance to really use it, yet. It came with an elusive and odd bug. The touch screen stopped responding once in a while. This could occur any time, but seemed to happen less frequently after 5-10 minutes of active use.
The first time I sent the phone to repair, it came back with flashed ROM, but the problem stayed.
The second time I sent the phone for repair, it came back with a new touch screen, but the problem stayed.