With the launch of any of the 5 Heroes games (original, expansions, unofficial expansions).

I got a licensed version of Tribes of the East, and the same thing happens!

What Tribes are you talking about??? I'm afraid to disappoint you, but this seems to be a pirated copy as well...
As for the problem... try deleting absolutely everything related to Heroes 5, then clean the registry using some program (to make sure all traces are removed), and reinstall it. Make sure the path to the game doesn't contain folders with Russian characters (e.g., C:\Games\Hero5). Then, apply the latest patch (1.6 patch for the original game (it's best to install the cumulative patch right away), 2.1 for Hammers of Fate, 3.1 for Tribes of the East). Let me know how it goes.

P.S. My licensed version with patches continued to work without problems after I installed SP3.