If you are using Vista with latest service packs installed there was a recent change in the way the action centre api reports things such as Firewall/Anti-virus.
PC Guard is now based on Kaspersky V6 which still reports to windows in the old way, therefore unless Virgin get the code changed just make sure it is running ok via task manager and switch of the reminders.
Give tech support a call like toto and Ben suggested or sack PC Guard alltogether and go for something like Avira/AVG or Avast for free AV coupled with Online Armour free or Outpost free, or maybe Comodo Internet Security for firewall, hips and AV for free.
What did you have installed security wise before you installed PC Guard?
Discussion on the security centre issue->
http://www.cableforum.co.uk/board/38...-pc-guard.html