random shutdown has been reported, so smoke over this thread for possible ideas. the handset always reads the external card upon power up unless the card is faulty or not seated properly. remove and reinsert the card as it could just need a re-seat in its slot.
if all of these issues started after the OTA update, its possible something could have gotten tangled (EM's words
) and a factory reset may be in order.
you could have an app causing this issue, so did this start to happen prior to an app install/update or uninstall?
really hard to troubleshoot across the internet but hopefully this thread and some of the ideas i mentioned (along with others who may follow) will help you decide the best action.