Heroes 3 issues under XP or Vista.

If you're using Windows 7 (and I suspect that's the case – it's a source of problems), try compatibility mode. Run the game in that mode. And by the way, I wasn't talking about Heroes Chronicles; I meant the Platinum Collection.

Here, take a look at what versions are available:

/topic/3165/

Added after 4 minutes
By the way, how did you manage to register on the forum so cleverly? :)