Use -option+S- at boot to enter in the single root mode.

Use -option+S- at boot to enter in the single root mode.

run those commands

To set in read and write the /
# mount -o update /

 /sbin/mount -uw /
# cd /Library/Preferences
# rm com.apple.loginwindow.plist
# rm com.apple.windowserver.plist
# cd /Library/Caches
# rm -r *
# cd /System/Library
# rm Extensions.mkext
# cd /System/Library/Caches
# rm -r *
# reboot