Heroes of Might and Magic V won't launch.

Help me! I recently bought a licensed copy of Heroes - Silver Edition. Everything is as it should be, with keys and logos from 1C and Nival. So... I installed the original Heroes, installed the patches - it runs. And even without the disc. I installed Hammers of Fate - it only runs with the disc. But if I install the official patch 2.1 for Hammers of Fate, the game doesn't launch! That is, the disc is in the drive, but it says "insert disc." And without the patch, it runs. What's the problem - help!