That looks like it might be the monitor’s own on-screen display rather than anything Puppy related. My guess is that the monitor hasn’t been detected properly and Puppy is putting out a resolution that the monitor can’t deal with.

Since the message says 1280x1024, either the monitor is 1280x1024 and can’t deal with anything else, or it’s not 1280x1024 and is being sent 1280x1024 resolution and is complaining about it.

(Or worse, it’s a clock frequency error which was a real problem back in the early days of Linux.)

As for how to fix, the answer is going to be different depending on the age of the base Linux under Puppy and the graphical subsystem.

For X/X11/Xorg it’s probably going to need use of the xrandr shell command, perhaps to delete the mode that is causing the problem. For Wayland, it appears that each window manager has its own xrandr equivalent. I see talk of a gnome-randr, for example.

To get to a shell in the first place, try the Ctrl+Alt+F1 key-combo. If the computer isn’t frozen, that might get a text-based console login prompt. (Puppy might do things differently here though. Not sure.)

Alternatively, look up how to boot to a single-user shell by modifying GRUB options, that is, if no such option is there already.

Caveat: I am no expert. Take this under advisement. Also try web-searching some keywords. It might be there’s a really simple fix for this that I don’t know about.

Looks like it’s using a video mode the monitor doesn’t support, you’ll need to set the refresh rate as well as the resolution to ones that are supported. Likely candidates are 800x600@75hz or 1024x768@60hz, but it really depends on the monitor, check the manual if you can

Try booting with kernel flag --nomodeset. If it gets you to the desktop, you could find out more about the graphics card and monitor.

Ooh, CRT monitor. And that’s an odd resolution that it’s suggesting. You could try driving it at 1280x1024 at 60Hz. If that doesn’t work, try 800x600 at 60Hz, which is the traditional lowest SVGA resolution (picture may be slightly distorted if it really is a 5:4 monitor). If that doesn’t work, try the traditional VGA resolution of 640x480 just to get something going. I’d recommend using X as Wayland has probably not been tested very much on hardware this old. And it almost certainly has no clue how to deal with a widescreen resolution or a resolution wider than its “Recommend mode”.

(I was still using a 17" CRT with X at 1280x960 up to about five years ago. I had no issues ever.)

This is the evidence that it was working.

The monitor seems to be recommending you use mode 1280x1024. Have you tried that?

Did you solved it?