The workflow I use on my macbook pro has me switching between applications using the 'command + tab' application switcher.

This is causing intermittent issues with UltraEdit. If UltraEdit has focus when I press 'command + tab' two windows pop-up. The window in focus says 'Search String ',' Not found!' Behind that pop-up is another window that says 'Press CANCEL to abort the current operation...' When I click the 'Ok' button on the 'Search String ',' Not found!' window both windows go away.

I checked the 'Key Mapping' in the UltraEdit 'Preferences' but nothing is currently using the 'Command + Tab' key combination. For the life of me I can't figure out what is causing this behavior and therefore I'm at a loss on how to stop it.

Can anyone provide any information on why this is happening?

You can see a screencast of this behavior here: http://www.screencast.com/t/yhMateNDY

command+tab works for me in OSX as it is meant to ... WITH UE running....

and I have NOT added or deleted any keyboard commands....

!! SOLVED !!
I finally figured out what was causing this behavior.

If I do a quick record of a macro and don't 'unload all' after I'm done with the macro then using cmd + tab is causing the macro to execute again.

I looked on the key mapping configuration and there is no mapping of any kind regarding macros and the cmd + tab key combination so I have think this is either a default shortcut or an undocumented feature (bug).

Try a test yourself. 'Quick record' a macro of some text input in UE (I recorded myself typing "Hello World!') Now 'stop recording'. Next try the cmd + tab key combination. Every time you shift focus away from UE the macro will execute. After a few tests choose 'unload all' from the macro submenu. Try the cmd + tab again. Notice that your macro is no longer executing.

you might want to send that directly to IDM as a bug report....

There are certain keys that need to stay reserved for OSX

Thanks, Dave.

I submitted a bug report to IDM.