I have in my hands many Desire phones who have this problem with reboot or lockup
All of them are with SLCD and most of them are grey. They just overheating too much compared to black ones with Amoled. Man in service told me that there is 2 or 3 different boards for Desire and 3 different displays. First series of desire are best one and they are all with Amoled displays and most of them are black.
Some models can`t even finish a flashing because they just reboot. To finish flashing put some cold metal under them from fridgerate
sound stupid but that helps... Phone working stable until is cold, after that random reboots again
I bought mine from guy in UK with UK charger when they starting to selling there on beggining. I personally don`t have any single lock up since than, except one lockup when phone was on sun and charging + gps + wifi on and OC to ~1200 mhz at performance mode. Guess that was too much.
I`m running moded Oxygen version from Roalex COS 17.04.2012. (update-oxygen_cos-17042012.zip + update) Best ROM ever for desire if you ask me, with ext3 1 GB enabled and installed 241 aplications only some are system apps!!! Don`t move ANY app to SD !! and it`s not DATA2SD !!! Use Autorun Manager to disable all useless startup apps and you will have 200-240 RAM free after all that apps are installed. Got FB, viber, WhatsApp and some others apps running all time in background. And you don`t need ANY task killer or something similar.
I even try ICS 10.01 and that working very nice finally, no lockups or reboot in 2 days, just a little too much battery drain for now
Waiting for some fixed release.
There is no real life, there is only AFK!