Windows 8.1 has a known issue with some software causing the screen to go black after logging in. (8.1 requires one to log on with Microsoft ID) I couldn't find info online (using a back up computer) on how to boot in Safe Mode. Called Dell support, computer was less than a week old. When booted in Safe Mode, they remotely looked at the few programs I had installed, (Open Office, Chrome & Spybot), and they immediately removed Spybot using Revo Uninstaller. The computer worked fine after that. In addition, Dell Support used software I've seen mentioned in another thread here on a Spybot forum to scan for malware, "Malwarebytes", along with AdwCleaner. Just passing on my experience.