Friends, I have a Sony VGN-AR51M which is running under Windows Vista. It has MS office 2007 installed in that. I got warning about virus infection while I was surfing on internet. I did the virus scan but nothing was detected. Now I have changed my virus protection to Microsoft Security Essentials (foc). After few days I found that the Windows Defender is turned off. I tried to turn that on but it shows me some error message that contains the code 0x800705b4. How can I fix this? Can it cause any problem to my system? Any helpful suggestion will be appreciative.