The computer system is windows10 1803 x64 pro with kb4340917 patch, remove IE、edge and defender, install comodo firewall, install avast_free_antivirus_setup_offline.exe ver18.6.2344, upgrade to 18.6.2345, black screen appears many times. The new system was restored, and the black screen phenomenon also appeared with the new installation 18.6.2345. In the same environment, there was no problem with avast 18.5.2342 and avast 18.6.2344.