[jblass]

My widescreen iMac (OS 10.4.10) suddenly began behaving as if the command key is pressed all the time. Clicking on an icon in the dock brings up not the application, but the application folder that contains it. (Option clicking on the icon brings up the app.) Typing an "n" in TextEdit brings up a new window, a "q" quits the app, etc.

The problem isn't in the keyboard, since a different keyboard produces exactly the same result. Any suggestions will be greatly appreciated, since this renders the computer completely unusable.

[dowNNshift]

Sounds like Sticky Keys is turned on.

To turn it off: Go to System Preferences >>> Universal Access >>> Keyboard Tab

Click on the off radio button. Sticky keys can accidentally get turned on if the shift key is pressed 5 times in a row.

[jblass]

Sticky keys are off.

[jblass]

Update: I restarted in "safe mode" by holding down the shift key during startup, and it worked properly. I removed all USB's except keyboard and mouse, and restarted in normal mode. It worked properly. I gradually reconnected the USB devices, and it's still working.

I'll never understand computers!

[P]

That is not a requirement to using them.

The most common cause for a stuck key is a keyboard malfunction because you've spilt something into it. If you can recall doing that, pick the keyboard apart and clean it.