Difference between XP and Vista/7?

[Shao Sean]

In all operating systems you are not supposed to modify content in the  
application (program files) folders.. While most systems are pretty  
relaxed about it, if the user trying to use your software does not  
have privileges to modify the content of the directory your scheme  
stops working..

In Vista (and I am assuming Windows 7) there is the lovely virtual  
store which might be happening with your code seeing as it works when  
on the desktop but not installed in the Program Files directory.. Try  
saving your license stack to a safe folder (appdata) and see if that  
works better for you..