This file started appearing on people's desktop after the April 2003, Cumulative Patch for Outlook Express (330994) update released by Microsoft. If that update is installed and you take any action that changes the Windows Address Book the
tilde file will appear on your desktop.
You can find out more about the update itself from the Microsoft page...
http://www.microsoft.com/windows/ie/downlo...994/default.asp
When you change the Address Book, what should happen is that a backup called YOURNAME.WA~ would be created in the directory C:\Windows\Application Data\Microsoft\Address Book. This is a backup to the Address Book named YOURNAME.WAB in that same directory. With the update installed, however, the backup does not get installed into the correct directory and the name gets shortened to just the ending
tilde (~) character. This file appears on your Desktop instead of where it should appear.