Well there's only 1 listing of svchost and it's in the \system32 directory so I don't believe there are any nasties lurking.
Just to make sure I have run various online scanners today in addition to a full scan with all of my utilities - just some simple tracking cookies.
I have disabled every service that is safe to do so and/or is unnecessary but the problem still exists.
Someone has suggested trying 'What's Running' so off to play with that ....