Hi mister.k. I suspect that the source of your problem is that the BIOS update has reset your BIOS settings to their default. I don't know if your Advent motherboard has onboard sound, but it is quite possible that it hs, and that you also have a sound card. this would be quite likely to cause this sort of problem. If you have no other way of finding what your sound card is, take it out of the case and see what is written on the chips. Post the results here and we'll see if we can identify the correct drivers.