Here's and Undo related bug on Internet Explorer.  It does not show up on the Mac.

Enter some text.  Switch to HTML view.  At this point Ctrl-Z does nothing.  Modify the text in the HTML view.  Then type Ctrl-Z to undo the changes and then type Ctrl-Z one more time.  On my machine the whole text will be lost (unless you type Ctrl-Y to redo).  This bug shows up in the editor for posting to the forums.

 

Keep hacking,

 

Randal..