welcome to the notepad++ community, @Richard-Linhart
i can’t yet reproduce that opening a .cfm file, causes an abnormal notepad++ shutdown.
please test the following, to verify, if a clean notepad++ (without any 7.7 incompatible plugins that could cause this) would be able to open them on your system.
download the notepad++ 7.7 portable version from >>> here <<<.
(the portable version does not require any installation and runs completely independent and isolated from your installed version. all custom settings, as well as any stuff you might want to try at the portable version, will not modify your installed version)
extract npp.7.7.bin.zip to your desktop.
important note: make sure to close all instances of notepad++ that might be running, before starting the portable version at the next step, to make sure you are using this portable version.
open the extracted npp.7.7.bin folder and start this portable version by double-clicking on notepad++.exe inside this folder.
(note: notepad++.exe will just be seen as notepad++, if you have enabled to hide all known file extensions at your explorer settings)
try to go to the menu file > open and open any .cfm file and report back what happens.
many thanks and best regards.