I've had that happen on Win xp in the past, and again recently on Win 10 - if you dragged a file with a filepath length (the whole c:\a\b\name.wav name) longer than 242 it would crash, and after restarting cooledit, or even windows, subsequently crashes on any attempt to drag a file regardless of name length.
The only solution I found was to completely remove cooledit, from the registry at least, & possibly required from Appdata & Program Files too, then reinstall. I made notes a while ago re Win xp and am just in the process of seeing if this procedure works on Win 10 too at the moment:
Cooledit may crash if try to drag (or batch convert) a file whose filename is too long (more than 242 chars)
When cooledit starts next it will ask if want old session, if say yes the long file will be loaded ok.
But all file dragging from then on can cause crash.
to fix this need to
end task cooledit in task manager
reinstall after searching for & deleting Syntrillium (usually 2 copies) from registry (must do that else still crashes)
and possibly (don't seem to need to do this part ) deleting doc&settings\mjs\appldata\coolpro2 too.
Install from cepsetup.exe of 10/4/2002 (Cool Edit pro v2)