Some cracked games aren't stable, so it will cause system
instabilities and result in BSODs of which you have to
restart.
If it restarts automatically halfway through a game, it's either
the programming flaw in pirated games which caused your PC to be
using so much system resources that it has no choice but to reboot,
or your PC is overheating. If you overclocked, please set them back
to the default settings.