Alright... Try running the game using different modes. Follow the steps below:
1) Create a shortcut to the game on your desktop.
2) Right click on the shortcut and choose "Properties".
3) In the target box after the last quotation, press the space bar once and type in the command lines below:
Windowed Mode: Your target line should look something like "C:\Program Files\Diablo II\Diablo II.exe" -w
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