Your system works fine, but it complains loudly about foreign software. Secretly, you wish it would.
Files disappear, only to reappear mysteriously a year later, in another directory.
You know it's guilty of trashing your system, but you just can't prove it. All files are reported as the same size. This revolutionary virus does not horse around. Activates every component in your system, just before the whole thing quits. Nothing works, but your diagnostic software says everything is fine.