Cannot boot on the fly. "StartImage failed: Not Found"

I haven't yet sorted out the pattern. But it surely appears when I reboot the system, and sometimes when I switch on my PC.
The only solution so far is to enter boot menu and select the hard drive and hit "Enter". Note that it is already prioritized and selected!
I have installed ZorinOS 17 Lite. It was a fresh install, no other systems are installed on the hard drive, and I have only one hard drive with ZorinOS on it.

Hardware Info of my PC:
P41T-D3P Motherboard
Core 2 Duo E8600
8GB RAM 1333MHz DDR3
Nvidia GeForce GTX 650

Additional software I've installed:
CopyQ
Ulauncher
Plank
... and some utility packages using "apt install"

PS It was a clean and fresh install, with wiping the whole disk, no dual boot, no nothing. Previously LXLE (other distro) was installed.

Based on the provided search results, here’s a concise answer to address the issue:

StartImage failed: Not Found in Ubuntu 22.04:

  1. GRUB corruption: The error message suggests that the GRUB bootloader is corrupted or missing. This can occur due to firmware issues, power failures, or failed updates.
  2. UEFI firmware: As Ubuntu 22.04 uses UEFI firmware, it’s essential to ensure that the firmware is up-to-date and compatible with your system.
  3. Boot Repair: Run Boot Repair from a Live USB/CD to fix potential issues with the GRUB bootloader. This tool can repair or reinstall GRUB, and also update the UEFI firmware if necessary.
  4. Check disk partitions: Verify that the disk partitions are correct and consistent. If necessary, use tools like sudo parted or sudo gparted to adjust or resize partitions.
  5. Reinstall GRUB: If Boot Repair doesn’t resolve the issue, you can try reinstalling GRUB manually. Be cautious when doing so, as this may overwrite existing configurations.
  6. UEFI settings: Ensure that the UEFI settings are set to boot from the correct device (e.g., SSD). You can access UEFI settings by restarting your system and pressing a specific key (usually F2, F12, or Del).
  7. System restore: If none of the above steps resolve the issue, you may need to perform a system restore to a previous point or reinstall Ubuntu 22.04 from scratch.

Additional tips:

  • Back up your data regularly to prevent data loss in case of a system failure.
  • Keep your system and firmware up-to-date to minimize the risk of issues.
  • If you’re dual-booting with Windows, ensure that the Windows bootloader is not interfering with the Ubuntu GRUB bootloader.

Remember to carefully evaluate each step and potential consequences before attempting any repairs or reinstallations. If you’re unsure or uncomfortable with these steps, consider seeking assistance from a qualified IT professional or Ubuntu community forums.

There is no UEFI. I have an old PC, it is legacy (BIOS), so the 2nd, 6th points are irrelevant.
(1) GRUB is not corrupted, otherwise I couldn't boot the system at all. In my case, I can boot the OS, but not on the fly, I am not sure if it loads next time. But this error persists when I hit the "Restart" button or run "reboot" command.
(4) Maybe, but I hadn't messed with partitions during the installation, I just selected "Use the whole drive/disk". And I hadn't screwed with partitions after the installation.
(7) How? Why? It is already brand new and fresh install, from scratch.

The only options that are left is GRUB. I've run the command "apt update" & "apt upgrade" & "update-grub". No affect on the boot process. Random failure "StartImage failed: Not Found" on switch on (meaning the PC if off and I press the power button), and same error for sure on reboots/restarts.

Is the BIOS up to date? Is the hard drive settings in BIOS set to RAID? If so change to AHCI.

Because of that: How did You installed Zorin? What Tool did you used? Have You used for the bootable Stick the MBR Partition Sheme?

Because of GRUB: The Grub seems to work, yes. But to try it with Boot Repair maybe affects a File (or some files) and then it could work normally again. when You already have a USB Stick with Zorin on, You can start Zorin in Live Mode (choose ''Try zorin instead of ''Install Zorin'') and take there Boot Repair. It is on the Stick.