One of my friends just chatted me online – the “Shift-S” keyboard sequence wasn’t working.
The “s” key works normally, it works with “Caps Lock, s”, but just not with either of the Shift keys.
I suggested that she unplug and replug the keyboard, and eventually I resigned to even rebooting the Mac.
Turns out that the issue is “Text to Speech” in the Speech System Preference:
This frustrated me also. I could not use the shift s key to get a capital s. Here is how I resolved the issue. It turns out that the s key was set up in the system preferences to speak selected text when the key is pressed. Here are the steps that I took to resolve my problem. Maybe it will help some of the other users.
Open System Preferences.
Click on the Speech icon.
Click the “Text to Speech” tab.
Check to see if the checkbox is checked for “Speak selected text when the key is pressed”.
If it is checked that means that a key, in my case the “Shift-s” key was selected. Just uncheck the box and you should have your keys function as normal.
Hope this works for those who seem to have a single key problem.
I found this on the Apple Discussions here.