Because spyware never sleeps...
Source:
Chicago Tribune
Computer users beware, the bad guys are lurking. Twenty-four hours a day, seven days a week, they’re out there, churning out programs designed to infect your machine.
If left unchecked, their handy work will infiltrate your computer, hijacking your systems for their own evil benefit. A mild infection can slow down your machine, create a barrage of pop-up ads, or disable your keyboard. In more extreme cases, your computer can become virtually inoperable, your personal information can be stolen, or your identity can be used without your permission.