paul.dll, the cracks also prevent it from being used, otherwise it would be impossible to run the game at all.
And Y, StarForce 3 was actually destroying legit customers pc's, it destroyed my optical drive, but with other it did even more damage, if it wasn't cracked i would've never played splinter cell chaos theory again (which i bought!).
Thankfully they stopped using that protection after awhile, I think the last big title using it was Colin Mcrae: Dirt. Though they included documentation with the game on how to remove it.
Also StarForce 3, prevented games to be played on 64bit systems, thus after it was cracked, splinter cell : ct was suddenly playable on a 64bit OS.