Random ban? (Diablo 2)

He began to pump a little magpie. At first I played solo, during the week, up to 25 lvl. Everything was normal.
Today, after the 25th lvl, I began hiking on the baal together with other players. Raised lvl to 36 within ~ 1-2 hours. Out of the game - ban.
Map hack or cheats were not used. I played through the D2NT manager loader only, for the windowed mode, and to throw off gear and stones on other characters. When logging in, it says "Your account has been closed. (8)"
How can you just give bans to players?
Account name: menagroth2