On the way home, my old HTC Desire had no reaction without any warning. So I made it force reboot, but then, out of the blue, some of its core applications, including gmail and even 3G, seemed to disappear. I guessed the phenomenon has got to do with the sd card because I've S-OFFed the device and moved some applications into the sd card using a2sd. So I tried to do "a2sd checkext" from the terminal emulator, which also had to be reinstalled, and narrowly avoided to replace it with a new one. All in all, however, I have to replace it as it's becoming too out-of-date to keep using these days.