Typically crashes would be due to interfering programs, drivers, damaged files, or a hardware problem. The system crashing and restarting can be a serious problem and require a local PC tech to best troubleshoot ( //support.blizzard/article/000210453 ).
Battle
1
Close all Blizzard processes. Press Ctrl+Shift+Esc to open the Task Manager. Select the Processes tab. ...
2
Navigate to the folder containing the Battle directory: Press Windows Key+R to open the Run dialogue. ...
3
Delete the Battle folder.
4
Run Battle and update the game.