Vince: see my last paragraph for how I turned it off.
I think I'm encountering a variation of the same problem.
In Multi-Edit, I have Undo and Redo assigned to Ctrl-Z and Shift-Ctrl-Z. These work fine, as long as TCmd isn't running. Just recently (I'm not sure how long ago), Shift-Ctrl-Z stopped working in Multi-Edit. Now, when I press it, every other press results in a ghost TCmd icon flashing in my Windows system tray (see video, if it will attach), while at the same time a ghost copy of my TCmd window also flashes. The alternate keypresses show no symptoms. My TCmd window is unaffected by the keypresses.
The .INI file had TrayHotKey=/ in the [TakeCommand] section. I tried removing the slash, and also inserting TrayHotKey= in the [4NT] section. With those changes, the TCmd window now alternately minimizes to the Windows tray, and comes back, when I press Shift-Ctrl-Z. Well, at least it works as advertised; but it doesn't help me with Multi-Edit.
Here's what worked: I set TrayHotKey=¢. (That's an Alt-KP-155.) Since I don't know how to do a Shift-Ctrl-cent-sign from the keyboard, that effectively disables it. Any special character should do the trick.