Is there any other way (Other then apcompat.exe) of making a program that I'm about to run think it's Windows NT or Win9x

I'm trying to run a program (which worked both under NT and 98 before), but now it crashes everytime I enter ANYTHING other than 0.. if I try a,b,7,. anything, it crashes.. but not with 0.. i'm not really interested why this is, I'm more interested in fixing it.

--Thanks in advance