DeckLink SP Card Drivers

I have Decklink SP card in my PC but have not used it for a while. When I can to use it with Premier Pro CS5 I could control my Beta machine (PVW2800P) but could not see any video on the capture screen and I could not capture any video. The decklink software also controlled the machine but I had no video signal. I tried installing the latest Blackmagic Desk top video software and drivers but not luck (it did not recognise the card) The trouble is now I cannot reload my original software because Windows will not allow software without digital signatures. Anybody have a solution?