You may notice that you have a tilde (~) character that keeps on showing up on your desktop. This character will show up on your desktop every time you make a change to your Windows Address Book which is used by Outlook Express. It is part of a security patch for Outlook Express for a bug which could allow an attacker to run malicious code of the choice on a user's machine. Unfortunately there is a bug for the bug fix as well!
When you make a change in your Windows Address Book file, Windows will make a backup of this file. The patch renames the backup file to ~ and saves it in the directory where you start your Outlook Express. Most people start Outlook Express from a shortcut on their desktop, so the backup file gets placed there.
You can remove this file but it’s recommended that you back it up first since it’s a backup of your Windows Address Book. I would rename it to something like addressbackup.wab so you will know what it is. Put the .wab extension on it to associate the file with your address book
There is also an update to the patch to resolve the issue. Install security update 823353 to fix the bug with the previous patch.