Thanks Mac The Knife - will explore that tomorrow.
I am yet to find a pattern to the issue.
It's one of those 'sometimes' issues which are always fun to track down.
For some strange reason when I terminate the instance of svchost that is grabbing the resources, the Audio drivers for the Soundblaster card decide that they are not present.
So I know it the instance of svchost that controls the SB services - well a fairly safe assumption.
But with XP Home the 'Tasklist' command line input doesn't exists as it does in XP Pro.
To confirm, those who are really interested in this problem and the history - read my moanings about the Netgear wireless card install on a recent thread.
That will tell you that this is a very clean XP Home SP2 installation. BIOS at the latest level, VIA chipset updated (drives the PCI/AGP slots), AMD Duron 1Ghz, 512Mb RAM, 40Gb HD / 38Gb spare.
The issue comes to light without the Netgear sw/hw, with all updates - particularly MS Auto updates, any virus, firewall updates disabled.
I may just reformat and put Win2K on this particular PC. Seems to be a lot less trouble. I am a great fan of Win2K as I was about 98SE - I think that Win2K was about the only OS that MS got about right !!
Of course they had years of testing it under the guise of NT !!