Juddering flight controls

GuysJust bought DA Fokker 100, and had to get rid of it because the flight controls juddered and just didn't work.Now I realise that this has spread to all the aircraft in my FSX. The flight controls judder but do not work, even when fully deflected.I need this to be fixed, but I know little about how to fix these things. Could it be my registered FSUIPC 4, could it be my Simconnect or FSX SDK?I'm using FSX SP1, but had to remove SP2 because my FSX wouldn't start when I downloaded it. Could that be the problem?I'm just about to delete Flight Sim and never play it again, so please help. I'm fed up of these stupid problems.CJ