Yeah, now the double clicking works for all file types again, thx !!!
But there is still a little problem with this:
as usual C::B is not loaded and you open a file by double click (.workspace, .cbp, .cpp and .h tested)
now the file/project is loaded and everything works fine with C::B
but the folder containing the file is still blocked (no reactions, no updating, just white screen) and after closing C::B this "file not found" error message still appears !!!
this is for any folder and also for the desktop when I open a file there by double click...