>Hi David,
>
>Actually after de-fragmenting the server and tuning virtual memory it just went away. But its a worry!
>
>Thanks for your help.
>
>Richard

Well I'd still suspect a screen or a browse somewhere - even if no-one's there. The tune-up would have reduced the refresh time. So may-be it'll come back :-(
But I hope you've nailed it anyway.
Dave