Winxp home and pro editions 32 bit = Works fine
Win 7 Basic and Premiun 64 bit = Works fine
I tested it with a nvidia geforce 8800 gs card , A mobile ati radeon 5450
and an Intel hd 2000 card and each one does not come up with any probs ,i have tried to create non power off 2 tilesets and huge textures but i still don't get the framerate problems.
Try to re install Classic Construct and see what happens.