Hi,
I have great experience in Windows API and I can definitely help you create an application that displays an error message when the system time reaches a particular date and time and prevents the user from continuing further. But we need to duscuss more on how this needs to be done in a proper way. I will write the application in C++, and the executable that you get can run in any version of Windows starting from XP.
Please feel free to contact me via chat, so that we can discuss further and start working on this interesting project as soon as possible.
Best Regards,
Aravind A