HoMM3 HD bug reports.

valtorna,
first, update the HD mod to the latest 4.207 RC3 version.
Your version 3.808 build 7 is very outdated.

Here: https://sites.google.com/site/heroes3hd/rus/download
download 4.207 RC2
then update through the launcher to RC3.
If the error does not disappear, then upload the save file and the crash log.

P.S. Nagabanks are not the problem. There is nothing wrong with their presence on the map, and there never has been.