How To clear the Past Items or Icons list in the TaskBar, perform the following steps:
1.Open Regedit (start > Run... >
regedit) and navigate to:
HKEY_CURRENT_USER\Software\Microsoft\Windows\Curre ntVersion\Explorer\TrayNotify
2.Delete the IconStreams and PastIconsStream values
3.Open Task Manager, click the Processes tab, click Explorer.exe , and then click End Process .
4.In Task Manager, click File , click New Task , type explorer , and then click OK .
If anyone "really" wanted to find it they could unless you destroy the hard drive in an apocalyptical manner.
A little registry cleaning might also help:
http://www.hoverdesk.net/freeware.htm
Like altering system files, modifying the registry can be risky and D-A-L.com and its members cannot accept liability for any adverse effects caused by following advice freely given on this site.