Register.UK: Windows XP crashed too much to spread WannaCrypt.

Kryptos (whose roster includes celebrated sink-holer MalwareTech) has bumped its head on this for an almost-comical reason: yes, WannyCrypt could infect XP machines, but the underlying DOUBLEPULSAR payload kept crashing the targets.

When Apple switched from System 9 to OS X, I moved over to Windows XP to (ostensibly sensibly) avoid beta-software issues. As I quickly found, XP needed at least fifteen minutes a day of system maintenance to keep the damned thing running. 

I'd have been better off with beta OS X. Sometimes cautious wisdom kicks you in the arse.