C key won't work except for entry mode

I reinstalled the program, and still the same issue. never had this before.
C on the keyboard (regardless to upper/lower case), won't work unless I input a C not in entry mode.
So, no C in rehearsal letters, chords or lyrics.

Anyone ever experience this?
so far I reinstalled the program, and double checked the shortcuts to see that nothing is funny there.
WeirD.