This morning we noticed that when the Event Viewer page does not show any events nor does it show any error messages. The events are still arriving in and are still accessible, just not through the default link in the menu bar. For the now I have created a temp page for the last 50 events today which works fine, except it doesn't have a search facility built into the page like the default one does.
When the page is requested the header and menu bars load ok, just there is no events or any search facility present. It's as if the link has become corrupt or something. Nothing to my knowledge has been changed, I was away last week and no one else admin's the system that was here.