I have a Dell Inspiron 17-5767 Laptop with Windows 10 home edition. I am trying to make it a Dual-Boot with Ubuntu 16.04.3 LTS Desktop. I installed Ubuntu using Rufus on a 32 GB USB.
When I plug in the USB and start with F12 option, it works fine and recognizes and runs Ubuntu from the USB drive. Then I installed Ubuntu on the hard disk letting Ubuntu split the hard disk and install alongside Windows 10.
Installation shows as successful, and hard disk space is broken up almost equally between two OS's. When I reboot after installing by hitting power button, a screen pops up (Magenta colored offering Ubuntu, advanced Ubuntu and Windows Server as options). Select Ubuntu, it starts up. Shut down, then restart with power, and the Magenta screen comes up again. Shutdown, select Windows, and Windows 10 pops up. Shutdown, Startup again, and this time you get no magenta screen offering options, only Windows 10 startup. If you restart using F12 repeatedly to activate BIOS settings, etc., only Windows 10 shows up as Boot system option. Run with Ubuntu USB drive in, and rerun F12 option, and it will recognize both Ubuntu and Windows.
If I use Disk Manager to review partitioning, it shows 16 GB swap and 868 GB other as main region for files under Ubuntu. If you reinstall Ubuntu, it seems to recognizes these partitions as previous Ubuntu installation, and will remove and reinstall at these locations successfully. So, problem seems to be after installation and startup with Windows, it no longer recognizes Ubuntu installation. This is with UEFI and Secure Boot disabled, including throughout installation.
What else can I do or what might be the problem?