Have you tried running the antispyware in safe mode? I have seen many cases when the scan is blocked or even the tool just closes (like when you end task from Task Manager), because of some smart malwares that detect the tool and block it. That's why it is best to scan for viruses/malwares in Safe Mode to minimize the chance of any malware running and interferes with the process. It's also a lot faster since most malwares are not loaded in RAM and they do not consume any resources.