Technical issues in Heroes IV.

The situation is as follows: I have a licensed copy of Heroes 4 from Buka. After installation and launch, I get a black screen, and the computer freezes. I read somewhere that a patch is needed (a different executable file, about 8 MB). When I run it, I get an error (I don't remember what it was). I reverted to the original executable, installed "The Warlords" from the disc, but it didn't help. The game still freezes the computer when launched. I was advised to install Equilibris. I downloaded it, ran install_Equilibris_v.3.51, and it gave me a checksum error, saying it doesn't match the reference version. I read on the download page:

Q: Despite having a working installation of Heroes IV, the installer complains - it doesn't like the checksum of the file. What should I do?

A: First, stop the installation. Then, just in case, copy heroes4.exe and campaign_editor.exe to a safe place (if you haven't already). Most likely, you just need to download the files heroes4.exe and campaign_editor.exe from the Downloads section. Extract them to the Heroes folder and run the installation again. There should be no more messages about an incorrect checksum, and the mod should install. Whatever the reason, remember that your old version of the game remains functional in any case!

I reinstalled the original game, downloaded heroes4.exe and heroes4 map editor.exe, and Equilibris installed without errors and runs. But when I try to start a TCP/IP server or a new game/scenario, it gives an error and crashes. Compatibility mode doesn't help. I decided to stop here and ask what to do next. P.S. - The original Heroes also works, but it also crashes when trying to start scenarios or the server. Windows XP SP2, single-core Celeron, NV7300gsPCI-E256mb video card, 17' 1280*1024 monitor. All add-ons for Heroes 3 and Heroes 5 run.