Boot problem with ubuntu MATE since install the latest version

Hello,

I'm new on the forum and new Ubuntu user.
Since I installed version 20, I only have startup problems. Indeed, I have to boot several times (3, 5 or 7 times) to finally appear a menu and only allow me to start in Rescue mode.
I reinstalled ubuntu 3 times and each time it's the same...

You will find below the link to the boot-repair application report
https://paste.ubuntu.com/p/sz8ssHbnGy/

and my configuration below

Unbuntu
Version 20.10 (Groovy Gorilla) 64bit
noyau Linux 5.8.0.25-generic x86_64
MATE 1.24.0

Matériel
Mémoire : 1,8 GiB
Processeur : Intel® Celeron(R) CPU N3150 @ 1.60GHz × 4
Graphismes : llvmpipe (LLVM 11.0.0, 128 bits)

In advance, thank you for your help

@Alexdici, welcome to the community.

It could be graphics driver issue. What do you have? llvmpipe is fallback. Many users with amd card are reporting issues if you check the forums. If you have NVIDIA or AMD did you choose install additional drivers option during install? If not, try doing so. Or, if you don't want to reinstall, try installing necessary drivers from recovery (after mounting rw).

VGA compatible controller Intel Corporation Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Integrated Graphics Controller (rev 21) (prog-if 00 [VGA controller])

Hello,

In addition, when I turn on the computer for the first time of the day, there is just a gray screen, I force it to turn off and as soon as I turn it on again it comes to GRUB and offers me two generic environments and two failure-free modes.
From then on, whatever the chosen environment is, it continues immediately on

Loading linux 5.8.0-25-generic...
Loading the initial memory disk...

And then, nothing more.

After several boots, it boots correctly and once booted, everything goes very well.
Thank you in advance for your help and have a nice day.