Unload the Debugger and Try again

[crispy]

There are several ways that protection mechanisms look for debuggers running in the background.
Frogsice won't help as it's out of date (won't help with sd2), and useless if softice isn't running. (Although it will log sd2's attempts to detect a debugger and could give you a clue to what's happening)

In the end, if you are playing from an original cd on a machine without a debugger present, then this is definitely a problem for the tech support of the software developer.

Ring them and pick their brains