Since my last bootloops (a week ago), I installed a pre-rooted stock Rom (no modification other than CWM and SU).
Yesterday morning, I take my phone (approx. half charged), and as I turn screen on : bootloop !!
Of course, since last week, I forgot to back up everything, so I got super bored to re-flash the phone. As this thread gave me a few leads, I tried to remove battery, sim card & SD card. Replace battery and reboot : no bootloop ! So I turned off always-wi-fi scanning-gps-buggy-thing, turned off the phone, replaced sim and SD card, turned on. Let's rock !
My conclusion :
The localization through wifi is responsible for the bootloops, although removing SD/Sim card (I don't know which one allows to break the bootloops, as I removed both) can help to access the system and turn off the service.
I will now backup everything (I still didn't do it), and maybe turn on again localization if I'm a player... :unsure: