KachiWachi:
I've set that setting (On Board Sound) in the BIOS to both enable and disable. It makes no difference. The Yamaha sound card was on the machine when it was purchased new (by me).
With the exception of a new floppy drive, a CD burner and a new Hard Drive, it's the same system. I cannot explain why the sound doesn't work. It worked IMMEDIATELY prior to the flash but not after it.