One reason why Xhibit is so unreliable...
... is that it only works with Microsoft Explorer, it's not eGIF (eGovernment Interoperability Framework) compliant, a standard that requires browser independence.
It was a major embarrassment for HMG when Xhibit was brought out and it was discovered (too late!) that many of the intended users couldn't use it... CJIT (Criminal Justice IT) had just assumed that everyone was a public sector employee using MS IE (duh!) but this was a mistake. For example, the Witness Service is provided by Victim Support, a charity, under contract to the Home Office, and many of their staff use FireFox, for all of the usual reasons - better security, more reliable, yada, yada, yada...
So much for Government denials that they are joined at the hip with Microsoft and have lots of warm and fuzzy feelings about Open Source... :-(