I created a group in the Microsoft Office Outlook 2003 shortcut navigation pane named "This & That," but each time I restart Outlook, the group name changes to "This & That" and I have to delete the excess characters. What causes this problem?

The problem you're having is a side effect of the fact that Outlook 2003 stores the shortcut navigation pane information in XML files—one for each mail profile that you use. In XML, the ampersand (&) is a special character used to help parse an XML document's content. Therefore, when you use an ampersand character in a shortcut's name, Outlook stores it in the XML as what's called an entity reference—specifically the string & (which you might also see in raw HTML pages).

The problem apparently is that when Outlook is restarted and rebuilds the Shortcuts pane from the XML file, Outlook isn't parsing & correctly and converting it back to &. Until Microsoft fixes this problem, the solution is to avoid using the ampersand character in the text for shortcuts.