third time was the charm. Not sure why it wouldn't stick before.
Anyway, it definitely seems to have resolved the problem! Guess there is no substitute for the real thing.
Many thanks for your help!
'fraid it didn't help .... it installed the driver and then Windows detected that it wasn't a 'Microsoft' driver and reverted back to the old one.
What's more, the problem seems to be a bit worse now ... :(
Maybe if there is some way to get the realtek audio driver to stick it might help.
I've catagorized this issue in "Video" because that is where it becomes most apparent, however it shows up intermitently throughout the day ... mostly when I am doing anything graphic intensive.
PC - Shuttle SX48P2 Deluxe
OS - Windows 7 Ultimate
RAM - 8 GB DDR3