桌面一直显示“your system is infected”怎么办？

桌面一直显示一黑框，上有红字“your system is infected”

system has been stopped due to a serious.Spyware activity has been detected
It is recommeded to use spyware removal tool to prevent data loss.
Do not use the computer before all spyware removed

请问有什么好的杀毒方法吗？