Mathcad window doesn't open. Please help.

I have had problems that occur directly after installation. I have uninstalled and reinstalled the game several times for it to work and it hasn't. Whenever I attempt to use it, the first window, the one that just says PTC Mathcad, appears and then disappears. That's all that happens, however. No Cad document, nothing. I am at a loss for what I should do.