Thanks, Memetic, good tip. I ran the driver update and got a "not enough memory" message.
I right clicked the file, then properties and tried various configurations on the memory tab, to no avail. The file size is 9.4 Mb - I tried 10Mb and also the max available (16384) in the drop-down lists in the Extended, Expanded and DOS Protected memory fields. I don't know what I'm doing here, so if there's an option I'm stuffing up some guidance would be very welcome!
Richard, the currrenty istalled AC97 driver version is 5.10.0.4050. The update is 5.10.0.5580. And the audio IS on board, not a card. The driver is specifically for the on-board audio. Also, using msconfig I unticked all the items in the Startup tab and rebooted, but no joy. Also downloaded a new copy of the file from a different mirror - same result. The computer is a Medion 8008, the mobo is an MSI 6A7I0M4M (reported by Fresh Diagnose) or MS-6701 (reported by Belarc Advisor) with SIS chipset.
Cheers
AA