Here's what viruses do:

1.They replicate quickly.

2.Viruses use up valuable system resources, slowing down the system as they do so.

3.Viruses will, from time to time, trash your hard disk.

4.Viruses are usually carried, unknown to the user, along with valuable programs and systems.

5.Viruses will occasionally make the user suspect their system is too slow (see 2) and the user will buy new hardware.

Until now it seems Windows is a virus but there are fundamental differences:

1.Viruses are well supported by their authors

2.Run on most systems

3.Their program code is fast, compact and efficient

4.Tend to become more sophisticated as they mature.

So Windows is not a virus.

It's a bug.