After upgrading an old Lenovo, I had serious issues with Windows 10 at startup that were usually related to a forced reboot (Windows Update restarting, etc.). After combing forums, searching Windows knowledgebase, and banging my head against the keyboard, I found two methods that worked. Method 1 has been most useful for me and continues to come in handy after unexpected reboots.
This article assumes two things: 1. your computer is an older model (BIOS not UEFI); and, 2. you are not afraid to try different fixes for a single problem.
Method 1
Change Display from Screen 1 to Screen 2
(NOTE: doesn't matter if you only use Screen 1, Windows 10 sets older graphics to Screen 2)
- CTRL (to set cursor to password box)
- Type user password
- Hit enter
- Wait (30 - 45 seconds)
- Win Key + P
- Down arrow (x2)*
- Hit Enter
*(NOTE1: if x2 is ineffective, restart, follow steps 1 - 5, then down arrow x1, step 7)
Method 2
Steps to Troubleshoot Driver Errors through Windows 10 Recovery Panel
(Note: Windows 10 updates may change video driver settings)
- Start machine
- After BIOS loads, hit F8 (opens Windows Recovery Menu)
- Troubleshooting > Advanced Options > Choose Account & Enter Password
- Wait for Windows 10 to do its thing: black screen, black screen w/ Windows logo, black screen w/ Windows logo and swirly dots
- Repeat 2-3 times, if necessary
Conclusion
Windows 10 was designed with modern UEFI systems in mind. Though the minimum specs may mean that an old computer can run Windows 10, the new operating system is not optimized for these older systems. In addition to video driver errors, the blackscreen at startup, and Cortana/Start Menu failures, older systems may also experience application crashes and an inability to use Hyper-V virtualization.