Heroes of Might and Magic V won't launch.

Six months ago, I had the same Windows version installed. After multiple installations and removals of various games, it started to glitch. I reinstalled Windows, formatted the drive, and installed a different Windows build. A couple of months later, I tried to launch Heroes, but it wouldn't start. I reinstalled Windows, formatted the drive, and installed the old Windows version – the game still wouldn't launch. I updated the video card drivers – still no luck. I updated DirectX – still no launch. I reinstalled Windows, installed new drivers, and DirectX from the disc – still no launch. After inserting the disc, a menu appears. I click "start game," and the disc starts spinning in the drive, then it stops after a minute. I open the Windows Task Manager, and there's a process in the system tray with the Heroes executable, consuming 50% of the CPU and 5.2 MB of RAM. If I don't terminate the process, it just sits there in the system tray, and nothing else happens. I can still use the computer and play other games (no frame rate issues with other games). I don't know which patch it is; it's the Heroes 5 disc from 1C. The box has a knight on it, with a castle in the background. Inside the box, there's a key for online play and a 1C registration form for registering the game copy. That's pretty much it. I'm waiting for help.