It doesn't just stop people from using ilegal copies of games, but also ones you pay for!!! My Caesar IV game disk won't work because a security program (secuROM) can't tell the difference between a copy and the original game disk. The support website doesn't help, telling me to change settings that are already on.
It's no wonder why gamedevelopers have been switching to creating their own security programes instead of using secuROM.