Running Windows XP, SP2. On august 17 downloaded a update from Microsoft (don't know what it was).Since that time I have no sound. Device manager states no working audio. Tried updating new drivers...not needed. Try a few restore points which would not take. Device manager states a code 10. Sound system does work on a reboot but only during the start as sound is being generated by the motherboard (i believe). Any ideas on how to correct this problem?