HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

Yes, it no longer crashes on startup. Thank you.

However, it still crashed during gameplay:

[HOMM3 HD CRASH INFO]

HOMM3 HD version: 2.98 (W7 fix 0.1)

Exception
{
   Module: 	MP3DEC.ASI

And if you simply extract the Mega Pack into the game folder, as instructed on the website, it won't appear in the "Your HoMM3 version" list; you need to manually move it to the correct folder.