i was having the same issue on the same model. I reformated my computer and it is working fine so far (knocks on wood) probably a windows update?
post here EVER, as everyone that have done some try could have the answer without knowing...
...i will wait for a new bios, but if marios can share the 312 for 504gw is a good thing for the owners of this laptop.
I have the 704gw so i can't install the eventual new bios that asus have installed on Marioos laptop.
for those who have send your device to service center but did not fix the problem,
please PM me your SN and RMA number.
I will confirm that BIOS 312 issue as well.
Really sorry for all the inconvenience caused.