Queue is not empty after probing

I'm running in a virtual machine for testing, but i did run on real hardware and the problem still occur, what stretch iso did you get the rt12 or rt13? can you send uname -a in a terminal and send me the the kernel information that pop up?
The error seems to come more often the less RAM i have available on the system, how much RAM have you got exactly?

I haven't been back to the workshop this week, but the iso i have installed is "linuxcnc-stretch-uspace-amd64-r13.iso", the PC was my workstation years ago, so there is plenty of ram at least 8GB or even 16 GB. It's there and I have no use for it, so i don't bother.

Could you remove some of your ram sticks and run the test again? I'm running with 2gb of ram

This machine is assembled about 2011, only alteration harddisk/SDD replacement. That is why i can not touch the running system. I also have a spare computer for any testing whatever i don't want to do on a working system.
But there is a mini itx board with arctic cpu cooler, the cooler must be removed to have access to the memory. 8gb installed.
All I can do, try this setup as is, if i can make it running, because odd, this setup produces joint following error, with the regular configuration used. Increasing ferror should solve that. I hope.
For the testing environment, i run Linuxcnc in Virtualbox 6 from Windows10, memory used increases from 3.7GB to 5.3GB. Maybe i was a bit generous,when configuring that.

But most Important, if you didn't test the memory with memtest at boot, it is the first thing to do now, for clarification of the state of the ram module.