Automatic Updates Service Fails

Hi,

Have configured WSUS on our network and after some initial hassle all now
works well except for a single XP Pro machine which cannot use the service
because...

Although the Automatic Updates Service is set to run automatically (GPO
controlled just like every other PC in our network), it does not. If you try
manually, it starts and immediately stops again, with a message that some
services do this automatically, etc. This one shouldn't.

The Event viewer system log shows:
Event 7036 (type: Information) "The Automatic Updates service entered the
stopped state." and the MS link says no action is requred.

Clearly this is not correct behaviour and it is unique to one machine of
many. Any ideas please anyone?

TIA

JC