Causes - Why Error loading operating system?
1. The BIOS of the motherboard is not compatible with the size of the hard disk or configuration.
2. The hard drive is not properly configured in CMOS.
3. There is something wrong with the hard drive partitions.
Solutions - How to Fix Error loading operating system issue?
Solution 1: Properly setup BIOS and CMOS
Because 1 and 2, update the BIOS on your motherboard if possible, by consulting your computer manual or visit the manufacturer's website, and go to the CMOS settings to make sure the hard disk is correctly detected and at the same time, change the "mode of access" Large or LBA to add support for large-capacity hard disk.