Speakers don't work with Messenger 4.7

I've seen a few cryptic questions about Messenger problems with Intel
network cards, but cannot find any details about it here or on Intel's web
site. My system is a new IBM ThinkPad T40p with on-board Intel PRO/1000 MT
Mobile Connection, and SoundMAX Integrated Digital Audio. It's running XP
Pro, with all the latest driver and critical updates, plus Messenger
4.7.2009. When I run its audio tuning wizard, no sound comes out of the
speakers, even though they work in other contexts. Is this a symptom of the
Intel problem and if so, can someone point me at an explanation of it?

Thanks, Keith MacDonald