[crispy]

At the edn of the day, there are many ways that progs can check for debuggers like SIce.
Checking Int handlers, driver names, vxds, softice dlls, etc etc etc. I would expect that since they've never installed sice or similar debuggers, then sd2 may be falling down over interrupt handlers in winxp (unless by some bizarre coincidence they have 3rd party software installed with the same named dlls, vxds etc as sice or similar debugger)

BUT, if these guys say they aren't running, or never have run SIce or any other debugger, then the people to call are the tech support of the games' publishers.
It's their problem for using a buggy and paranoid protection mechanism in the first place. And sadly if they can't help ya, it's gonna be difficult for us to sort you out at a distance.