I assume that you mean Nagravison3. Nagravison3 is a Conditional Access System. Virgin have replaced Nagravision1 with it. This means that boxes that could get around Nagravision1's encryption do not work any more.
There is no fix to this and no prospect of a fix because unlike Nagravision1, Nagravision3 has not been compromised is is unlikely to be in the near future.
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