Ok. Those repositories look good.

Is it such a hard lock that Ctrl-Alt-F1 doesn't take you to a terminal?

Does Gimp crash on opening, after a random period, on a specific function, or something else?

Have you tried running Gimp from the command line and seeing if it generates any errors or warnings there, perhaps redirecting the output (inc. stderr) to a file so that you can retrieve it after the hard lock?

Hi,
Creating some error logs is my next step..

Gimp was crashing the laptop solid, only a hard power-off (press & hold the power button) would do anything.
Screen pointer locked, unable to kill X with Ctrl-Alt-Backspace and no virtual terminals via Ctrl-Alt-Fx.
This happened on trying to load a known good png file.

I'm suspicious of some of the later kernel code for c and p state control for Intel Kaby lake (laptop is an Intel Core i7-8550U with UHD620 GPU.). [Looking at Intel for this ;>) ]

Briefly, I can't use the highest resolution that my screen can handle (1920x1080) unless I use the kernel boot parameter
The screen at 1920x1080 (no cstate parameter used) is virtually unusable, severe flickering, blanking out and "ghosting" from previous screens.

Dmesg (in Slackware) gives this (with no cstate boot parameter used):
Weirdly, Devuan ASCII runs perfectly fine at 1920x1080. Even when running the latest stable kernel.

Anyway, A disk check after the crash showed some file corruption (I'm using Ext4) within Gimp.
I therefore purged and reinstalled Gimp.
It still crashes the system when loading a png or a jpg, but I can now kill the X server and restart it.

I'll look again with the cstate boot parameter and a few other things that I want to try.

Earlier kernels (4.18.16 and earlier) are fine. I'm running the laptop at a lower resolution for now as I want to see how long it is before this is sorted.
I get better performance from the latest stable kernel as well as the release candidates so I'll stick with these for now.

Bodge99

I've sorted the Gimp problem..

Just for completeness.. I don't like hijacking threads, especially my own.

I spent a bit of time creating and examining error logs.. Nothing really jumped out as problematic.
I then tested Gimp in my other 19.1 installation. Guess what, it ran perfectly fine, loading in images that would crash the other Gimp previously.

Next, I returned to my main 19.1 installation and added a new user. Yes, Gimp ran perfectly.

I then examined the config files in my home directory, most seemed perfectly fine but I did notice that some files predated the Mint creation/installation date.

Lightbulb moment! I think that I've worked out what happened (and yes, it was my fault.)

When I upgrade or change my "working" distro, I create the users as per normal and then manually copy over a few things to the new home directories. These include all of the browser and mail configs etc. as well as any project files that I'm working with at the time.

On this occasion, It looked like I'd copied over more than I thought I had. Some stale configuration files had over written some of the newer ones.

Now that I know what the problem is the fix is easy. Backup important stuff (browser, mail and project files).
Delete and re-create the user (me). Finally, copy back the important stuff.

BTW. If anyone wants the latest version of Gimp, (uninstall the current version first!) it can be downloaded from https://www.gimp.org/downloads/
The current stable release is 2.10.8 (2018-11-08) and is available as a flatpak build suitable for Mint 19.1 .

Bodge99

Nice one.