Left and right arrow keys are not working properly now

Question

I searched the forum and didn't see this posted. My left and right arrow keys are not working properly now.
For example, when typing, left arrow does not produce the desired action (move cursor one spot to the left), and right arrow does not produce the desired action (move cursor one spot to the right). Also, control + left no longer activates spaces, and control + right no longer activates spaces.
Interestingly, in investigating the problem, I noticed that my shortcut keys for activating spaces and for activating expose had been changed (software update?). Before, I had set F5 (without pressing fn) for expose and had set F6 (without pressing fn) for spaces. Now, I noticed spaces was set back to the default of F8 (requiring fn).
The issue persists after shut down, and even when logged on to other users, e.g. Guest.
All other keys seem to be working fine, including the up and down arrows.
I don't think it's a cleaning issue because fn + left + right produces the "[" character on the screen.
Any ideas?

Answer 1

I'm having the same type of issue on my MacBook except not with arrow keys. The volume keys do different things when I click on them. For example, the mute key brings up the dashboard and the volume up key makes all the open screens smaller (don't know what this feature is called). I did a software update then restarted the computer when this starting happening. Any help would be greatly appreciated, thanks.