Dear guys, I dun think I solved it for everyone, but I think there is a Windows-related error with this. I had Diplomacy since like 2009, played it well, tried a ton of mods on it, gave them up, so basically a lot of changes and all went well.
Suddenly, one day it would just not enter. Reinstalled... nothing new. Forgot about Diplomacy around last year's December.
Bought Rebellion. Worked on campus laptop I have at University. Came back to me home town, installed it on me way-better-PC" . . . Guess what? Hell no, black screen bug affected it too. :/
Took on me usual weapon: regestry cleansers, used CCleaner, bought RegTweaker, fixed all errors they found, Virus/Rootkit scan, etc. (no defrag yet). Laptop felt as new. Done so at home, guess what, I got rid of dem bug.
Me opinion? It could be no game-related bug, which can be explained by why dem devs didn't find the source yet
I tried it and it worked ^.^
(Hopefully one will give me a link or sth related to some new Advent PvP builds as thanks and hope it will work fer ya)