I am using Windows 7. I had no antivirus program installed on my system except Microsoft Security Essentials. It came with the operating system. It looks like a antivirus by Microsoft but I am not sure that this might be so strong. Because when I am scanning I am getting a error in this. The error is 0x80508023 Microsoft Security Essentials couldn't scan your computer. Should I switch to anyother good antivirus program or this can be fixed.