My Mac is suffering from a keyboard key mapping problem. I don't know what system update or application update that changed just one key mapping: the "c" key
Now whenever I press the "c" key under "U.S." keyboard layout and "U.S." input source, NOT the "U.S. international-Pc", it refuses to output the normal "c" character but pop-ups a list of the accented version for me to choose. It can't seem to be fixed by tweaking input sources in system preferences | Language & Text.
This never happened until today and I don't recall doing anything special to have caused this.