Sir, after Portico update your phone will not have this issue (or it will be severely limited )
the cause of this is mainly related to Wlan+bluetooth and NFC drivers which are being worked on around the clock at Microsoft .
That was interesting and post #21 as well, hopefully MS will find the root of all this very soon....i do have both wireless/bluetooth on at all times so this is maybe why i see it a little bit more. Hopefully updates to apps are going to start arriving because too many are old and not made for WP 8.I had the Portico update and just had a black screen phone freeze last night. None of the buttons worked and the Unit didn't power on. I had to do a soft reset by holding the volume down button and the power button for a few seconds.
I found a solution! Finally... You need the Nokia Software Updater for Retail to flash the latest available firmware to your Nokia phone. The new firmware (version 1232.5957.1308.0001) has stopped the brick mode in its tracks. There are a lot of sites advertising this software, but all that I found require registration or the downloading some additional software. You can download the working retail version 2.0.6 here -- without registration and without any additional garbage software. It will update itself to 3.0.4 (or the most current version). I have run it on Windows 8 and Windows 7, connected to my unlocked Lumia 920 (RM-821_apac_philippines_388) and it works great. Firmware updated and it hasn't shut down since!
Hello Charles! Using an official piece of Nokia software (that checks the compatibility with your phone) to flash the latest released Nokia firmware will NOT void your warranty. I have updated my site with the latest progress and also address the scare tactics (no warranty, dead phone, etc.) here.
I also share some personal stuff about me on the right side of the page (Philippines, etc.) Good luck!