Thanks Richard.
Your Realtek link got me to an AC97 update package that worked, so thanks for that - that new driver has a number of excellent features. However, updating the mobo and sound card drivers didn't fix the problem in regard to the Nero 6 update. A reinstall of the OS (see below) didn't fix it either, so I've decided to live with ver 5.5.10.7
I put the Nero upgrade aside for the moment and started playing around with Windows Media Player. For some reason it had stopped playing streamed audio. Every time it connected it shut down with a nice polite apology, but always the failure was in the same mode, reporting an unhappiness to do with mplayer.exe and ntdll.dll.
The research I did on that suggested a repair of Windows was the way to go (reinstall of XP over the top of the current one.) Didn't work, did it.
It kept failing in the last 5 minutes in the "finalising" segment.
That led to a format and re-install, and I took the opportunity to trim the installed software - even less than what it came with. Amazing how much faster it is without the extra baggage.
But there is an issue - I'll start a new topic for it.
Cheers
AA