That's because you didn't used to run it on W7.
Welcome to the brave new world of Windows.
Instead of just clicking "Run as Admin..", in the same pop-up, click Properties>Compatibility, and check the Run as Admin box.
Beyond that, I'd be surprised if you didn't run into some odd behavior running a program that old in a 64 bit W7 environment. You might want to consider upgrading to a current version that is designed to run in that environment.
The basic version is cheap, and it has rubber tires now

.