Solved I need help

@enemy2452, make sure you uninstall any current game folder you have in your computer and and remove the registry files as well from HKEY_CURRENT_USER\Software\Blizzard Entertainment\Diablo II
Next, perform a clean reinstall of the client in a different location such as C:\NewFolderName and apply our server patch.
Set compatibility mode in case you need it to and run as administrator. You can create a shortcut of game.exe and add -w to run the game in window mode.
If it worked fine the other day then I'm assuming some recent software you may have installed created some sort of conflict with the game files or they got corrupted. Someone I helped recently with the same problem you're having installed a different game mod and caused a conflict with his other diablo clients he had already installed, another one had the wrong DEP settings set for his applications.

 

It says that some 3rdparty software triggered the anticheat and maybe it's trying to inject into various applications such as your browser, the game, etc.
Looks like a false positive alert so nothing to worry about, just run the game again. Check your PM and I'll have a look.

Solved, he had multiple diablo folders installed and the the wrong folder was being executed when the game was being launched. Removed the additional folders and reinstalled the game into one folder.