Copy-protection

Hm
Has any of you ever kept himself busy cracking copy-protections? Well, I have. But now I've come across some code-changing code. Very confusing to trace. Has anyone got suggestions of howto retrieve the *real* original code? I have allready tried disassemblers, but you still can't run the code without probs. The code checks up on the step-by-step flag. Obviously, when tracing, the code detects it's being traced. Wouldn't there be a way to lure the code so it thinks it's not being traced, but is?

Enlighten me!

Grtz,